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#1
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Posted to rec.audio.high-end
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To the group:
I have had 3 posts that I can still find not show up in this thread, or not get acknowledged, so I would like to re-send them one at a time and just complete the thought, as it were. Here is the first one: "KH" wrote in message ... On 5/28/2012 9:37 AM, Gary Eickmeier wrote: Hello again Keith - Thanks for the frank and honest reply. This is what I thought was going on, but I didn't think anyone else realized it. Gary, please re-read your last sentence in the context of "us" as readers, not you as author. Do you not see how implicitly dismissive it is? That is why I "beat you up" about being condescending previously. I've been around long enough to remember your earlier forays here, and as I recall, they devolved similarly. You would do yourself a service if you would take more care in tone. Sorry Keith but I really do have something to say. Please stay with me for this one last post - we are 99% of the way there. snip That's not idealism, Gary, that simply ignoring that there is no "right" when it comes to listener preference. There are a hundred Grape flavors. Do you believe there should be some unifying theory that would result in the one, true, grape flavor and everyone would then agree with that selection? If you and I disagree about which grape is the most realistic, is one of us wrong? If you and I disagree about whether a specific stereo implementation is realistic or not, is one of us wrong? If your answer to either question is "yes", further discussion is pointless as you're now in the realm of ideology not acoustical theory. OK, you are saying designing or selecting speakers is like selecting ice cream flavors at Baskin Robins. Well, I have another analogy for you, and I think it is quite apt. I have said that the stereo signal is a concentrate, to be mixed with the playback room acoustic in a certain way, a way that models itself after the real thing. Imagine two orangeophiles who are unfamiliar with frozen orange juice. They love their pure, rich Florida orange juice and they are yearning to duplicate it. So they select some Sunkist frozen juice and take it home to their tasting room. The first one takes his can, opens it, and starts eating the frozen slush straight out of the can. He figures that if this is made from the real orange juice he wants to take it straight, for the most accurate experience of the product. The second orangeophile says no no, you've got entirely the wrong idea. Watch me. We take the can of frozen concentrate, dump it into this pitcher, then add a quart of water and mix it in. The first man is horrified at the inaccuracy of consuming the pure juice that way. The second one explains why it works that way: He says it may not be as accurate to mix it with all this water first, but by doing so it is more realistic, much more like the original orange juice that it was made from and that we are trying to duplicate. Its temperature is more like the original, and that is feelable. Its texture is more like the real thing, and that is visible. Its flavor is more like the real thing, and that is very tasteable. You may prefer a California product, but we must all understand the basic principle of mixing it with water in this certain way before we consume it, no matter who made it. (where did the recorded ambience info go) It got converted into two dimensions. Basically, level and arrival time. How do you think incident angle information is coded into the signal? That's the HRTF information that is lost in the process. Not because it wasn't in the venue, and not because the microphone didn't pick it up, but because it was transduced using a very different instrument than WE use to hear. Here you have a technical misconception. Stereo has nothing to do with HRTF. That is a binaural, or head-related, process. With stereo, a field-type system, we are reproducing the object itself in front of us and using our own natural hearing mechanism and HRTF to listen to it. Why do you keep conflating stereo and binaural, and assuming everyone but you confuses the two? If you believe all the spacial clues are in a stereo recording I would submit that the confusion is yours. snip Then I would say that your whole approach is one of redefining what you think live music *should* sound like. How can one consider the real event to be anything other than the intended *end* point, not a "stepping off point"? Slight miscommunication. Although the reproduction is a new work of art, some works are made with the goal of the realistic reproduction of the original, some are a pure construct, such as a synthesizer composition or a multimiked and highly produced pop or jazz piece. It's all fair game. The point you repeatedly overlook - audiophiles, IME, all have the exact same design goals; faithful reproduction of the recorded event. They have different *preferences* that impact how they perceive the various implementations designed to realize that goal. *Most* are right - "trick", "illusion", call it what you will - that is the goal of stereo. You seem to want to disconnect the reproduction from the event, preferring to consider the reproduction paramount, and massaging it to meet your interpretation of realism; an interpretation untethered from the seminal event, and unconstrained by the desire to faithfully recreate it. This concept is at odds with the goals of every audiophile I know, or have conversed with. If this is, indeed your view, then I hope you like the role of Sysiphus. OK, here comes my main point of this whole discussion, my "closer." We have discussed all of the audible parts of the listening experience in the EEFs, What Can We Hear. We said that the spatial part is the main stumbling block, the main difference between the reproduction and the real thing. Think of it as pure physics. If the spatial qualities I discussed are audible, then we must make some attempt to reproduce them. The "real thing" comes to us as a primarily reverberant field from a multiplicity of incident angles. The reproduction comes to us from just those two points in space. That difference is seriously audible; they CANNOT sound the same. This is not a matter of taste, it is a fundamental error in the theory of reproduction. What to do, what to do? Look at the spatial problem from the standpoint of the image model of the real thing and the reproduction. If you can separate out in your mind the spatial from the temporal for a moment, and if the recording really does contain some of the early reflected sound from the venue, then it is more correct to reproduce that part of the sound by reflecting it from the similar surfaces in your listening room. Also, due to the closeness of the speakers to you, it is more correct to diminish the direct to reflected ratio emanating from the speakers. Design a certain radiation pattern according to Mark Davis that helps the time/intensity trading and image stability as you go across the room, pull the speakers out from the walls to make the soundstage three dimensional with similar depth and spaciousness to the real thing, and you are almost all the way to Image Model Theory, or IMT. There are many, many more aspects of this that are worth discussing, but I must leave it there for now. Thanks for listening. Ah, but whereas taking "the huge, wide set of fields that were recorded and pipe them all through just two points in space" split in some ratio between sound radiated directly at the listener and sound directed toward the front wall and then listening to the reflected simulation of the reverberant field is more accurate? Really? This approach adds spacial clues that are NOT in the recording, and thus cannot be accurate. There is no information in the recording that can be used to correctly "calibrate" some split of direct versus reflected sound to equal the spatial information in the recording venue - it's simply artificial. You may prefer the result, great, it's right for you, but you have no reason to assume that it is universal for other listeners. Looking across current speaker designs, it would seem quite the opposite in fact. Yes, I know. Keith Gary |
#2
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Posted to rec.audio.high-end
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On 6/9/2012 2:09 PM, Gary Eickmeier wrote:
To the group: snip If you and I disagree about which grape is the most realistic, is one of us wrong? If you and I disagree about whether a specific stereo implementation is realistic or not, is one of us wrong? If your answer to either question is "yes", further discussion is pointless as you're now in the realm of ideology not acoustical theory. OK, you are saying designing or selecting speakers is like selecting ice cream flavors at Baskin Robins. Well, I have another analogy for you, and I think it is quite apt. No, I did not present an analogy. I asked a very simple, probative question and your analogy does not address it. Why continue to duck the question? I have said that the stereo signal is a concentrate, to be mixed with the playback room acoustic in a certain way, a way that models itself after the real thing. That you have *said* in no way makes it valid. snip (where did the recorded ambience info go) It got converted into two dimensions. Basically, level and arrival time. How do you think incident angle information is coded into the signal? That's the HRTF information that is lost in the process. Not because it wasn't in the venue, and not because the microphone didn't pick it up, but because it was transduced using a very different instrument than WE use to hear. Here you have a technical misconception. No, here you have a communication issue. Stereo has nothing to do with HRTF. As has been stated repeatedly. You asked "where did the recorded ambiance go?". The answer is that the "ambience" is related directly to the HRTF of the listener in the venue. Sans listener, there is *ONLY* temporal and level data available for recording, and when recorded as such, this data cannot subsequently be used to accurately reproduce incident angle information. That information is lost in the translation. That is a binaural, or head-related, process. With stereo, a field-type system, we are reproducing the object itself in front of us and using our own natural hearing mechanism and HRTF to listen to it. Yes, that is the problem. The signal presented to the listener, in the venue, has angular, temporal, and level clues that, in conjunction with the HRTF of the listener, create a spacial image. That information was not, however, encoded into the recording except as temporal and level information. No matter how that information is played back, the signal reaching the listener cannot be the same as in the venue. Reflecting the sound cannot, except in the context of listener preference, ameliorate this constraint. snip OK, here comes my main point of this whole discussion, my "closer." We have discussed all of the audible parts of the listening experience in the EEFs, What Can We Hear. We said that the spatial part is the main stumbling block, the main difference between the reproduction and the real thing. Think of it as pure physics. Feel free to present some, please. If the spatial qualities I discussed are audible, then we must make some attempt to reproduce them. We can't reproduce them, they are not on the recording. What we can do is to produce an illusion, the efficacy of which is clearly a function of both engineering efficacy and listener preference. The "real thing" comes to us as a primarily reverberant field from a multiplicity of incident angles. No, it does not, except in a narrow subset of live events. Many times the direct component (lets think of outside live events for example, shall we?) is the dominant component, and sometimes by wide margins. The reproduction comes to us from just those two points in space. That difference is seriously audible; they CANNOT sound the same. This is not a matter of taste, it is a fundamental error in the theory of reproduction. It is not an *error* in theory, it is a physical constraint. You need to understand the difference. The fact that the reproduction cannot be the same as the original necessitates that listener preference play a pivotal role in assessment of the realism of the reproduction. What to do, what to do? Look at the spatial problem from the standpoint of the image model of the real thing and the reproduction. If you can separate out in your mind the spatial from the temporal for a moment, The distinction is clear in my mind, but that differential information is not present on stereo recordings. You need to clarify, in your mind, that there is no spacial information in a stereo recording. All spacial clues are translated to temporal and level information. If you disagree with me, then pray tell me, what portion of the recorded electrical signal - which is all we have after all, come reproduction - represents spacial information, *separate and unique* from temporal or level information? and if the recording really does contain some of the early reflected sound from the venue, It does contain it; translated into TEMPORAL and LEVEL information. then it is more correct to reproduce that part of the sound by reflecting it from the similar surfaces in your listening room. You are not reflecting *that part of the sound*, you are reflecting ALL of the sound, and in doing so, you reflect the DIRECT portion of the signal as well. That is clearly inappropriate - it doesn't come to you that way in the venue does it? If the spacial is as important as you maintain, then reflecting the direct portion of the signal is at least as egregious an error as ignoring the reverberant part of the signal. Keith |
#3
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Posted to rec.audio.high-end
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"KH" wrote in message
... On 6/9/2012 2:09 PM, Gary Eickmeier wrote: Yes, that is the problem. The signal presented to the listener, in the venue, has angular, temporal, and level clues that, in conjunction with the HRTF of the listener, create a spacial image. That information was not, however, encoded into the recording except as temporal and level information. No matter how that information is played back, the signal reaching the listener cannot be the same as in the venue. Reflecting the sound cannot, except in the context of listener preference, ameliorate this constraint. Keith, I'm not sure what exactly your conceptual problem is, but everyone knows that stereo operates on temporal and level differences between channels. You have noticed how those differences can cause the perception of phantom images between the speakers, right? That spatial information is encoded into the channels by means of temporal and level differences in the signals. Now, I have observed that reflecting a part of the sound from room surfaces can cause an image shift toward the reflecting surfaces. This has a twofold perceptual impact. One, it causes the sound to go outside the speaker boxes and appear as an aerial image somewhat behind the plane of the speakers, seeming like the instruments are right there in the room with you, rather than coming from speakers. Secondly, it causes an impression of spaciousness in recordings that contain such information, such as correctly miked symphonies in a good hall. Most of us have experienced this very audible difference between directional speakers and more omni type speakers. OK, fine, now between those two types of sound, one is likely to sound closer to live than the other. If you think that is just a preference and worth no further study, then that is the bed you shall lie in. If I think this is a significant point and worth further study, and try to get others to notice these effects and help me out, then please don't tell me it is all pointless because you are not interested. Audiophiles have been trying to figure out what causes these effects for decades. They have complained about boxy sounding speakers and the hole in the middle effect and wondered what makes some systems sound more realistic than others. My theories answer some very basic questions about very audible effects, and should be studied further. Yes, more psychoacoustic investigation is called for, to test these effects of reflected sound w respect to the playback situation. No, I have not and cannot do it all on my own. But I need some of those who can do it to pay attention and see if some of my suggestions on speaker placement and radiation patterns and room treatment could be true, so that it might help engineer the installation of stereo systems and the development of new speakers and maybe recording techniques. It's a whole deal. Gary Eickmeier |
#4
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Posted to rec.audio.high-end
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"KH" wrote in message
... On 6/9/2012 2:09 PM, Gary Eickmeier wrote: Yes, that is the problem. The signal presented to the listener, in the venue, has angular, temporal, and level clues that, in conjunction with the HRTF of the listener, create a spacial image. That information was not, however, encoded into the recording except as temporal and level information. No matter how that information is played back, the signal reaching the listener cannot be the same as in the venue. Reflecting the sound cannot, except in the context of listener preference, ameliorate this constraint. Keith, I'm not sure what exactly your conceptual problem is, but everyone knows that stereo operates on temporal and level differences between channels. You have noticed how those differences can cause the perception of phantom images between the speakers, right? That spatial information is encoded into the channels by means of temporal and level differences in the signals. Now, I have observed that reflecting a part of the sound from room surfaces can cause an image shift toward the reflecting surfaces. This has a twofold perceptual impact. One, it causes the sound to go outside the speaker boxes and appear as an aerial image somewhat behind the plane of the speakers, seeming like the instruments are right there in the room with you, rather than coming from speakers. Secondly, it causes an impression of spaciousness in recordings that contain such information, such as correctly miked symphonies in a good hall. Most of us have experienced this very audible difference between directional speakers and more omni type speakers. OK, fine, now between those two types of sound, one is likely to sound closer to live than the other. If you think that is just a preference and worth no further study, then that is the bed you shall l ie in. If I think this is a significant point and worth further study, and try to get others to notice these effects and help me out, then please don't tell me it is all pointless because you are not interested. Audiophiles have been trying to figure out what causes these effects for decades. They have complained about boxy sounding speakers and the hole in the middle effect and wondered what makes some systems sound more realistic than others. My theories answer some very basic questions about very audible effects, and should be studied further. Yes, more psychoacoustic investigation is called for, to test these effects of reflected sound w respect to the playback situation. No, I have not and cannot do it all on my own. But I need some of those who can do it to pay attention and see if some of my suggestions on speaker placement and radiation patterns and room treatment could be true, so that it might help engineer the installation of stereo systems and the development of new speakers and maybe recording techniques. It's a whole deal. Gary Eickmeier |
#5
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Posted to rec.audio.high-end
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On Mon, 11 Jun 2012 06:07:29 -0700, Gary Eickmeier wrote
(in article ): "KH" wrote in message ... On 6/9/2012 2:09 PM, Gary Eickmeier wrote: Yes, that is the problem. The signal presented to the listener, in the venue, has angular, temporal, and level clues that, in conjunction with the HRTF of the listener, create a spacial image. That information was not, however, encoded into the recording except as temporal and level information. No matter how that information is played back, the signal reaching the listener cannot be the same as in the venue. Reflecting the sound cannot, except in the context of listener preference, ameliorate this constraint. Keith, I'm not sure what exactly your conceptual problem is, but everyone knows that stereo operates on temporal and level differences between channels. You have noticed how those differences can cause the perception of phantom images between the speakers, right? That spatial information is encoded into the channels by means of temporal and level differences in the signals. You both forgot phase differences. |
#6
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Posted to rec.audio.high-end
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On 6/11/2012 6:07 AM, Gary Eickmeier wrote:
wrote in message ... On 6/9/2012 2:09 PM, Gary Eickmeier wrote: Yes, that is the problem. The signal presented to the listener, in the venue, has angular, temporal, and level clues that, in conjunction with the HRTF of the listener, create a spacial image. That information was not, however, encoded into the recording except as temporal and level information. No matter how that information is played back, the signal reaching the listener cannot be the same as in the venue. Reflecting the sound cannot, except in the context of listener preference, ameliorate this constraint. Keith, I'm not sure what exactly your conceptual problem is, I'm tempted to believe you. Not convinced, but tempted. I would posit, however, the conceptual difficulty appears to be yours. but everyone knows that stereo operates on temporal and level differences between channels. You have noticed how those differences can cause the perception of phantom images between the speakers, right? That spatial information is encoded into the channels by means of temporal and level differences in the signals. Then quit asking questions like "where did the information go?". The spatial information you are describing is left/right - that's it. That information *is* encoded in the signal. Up/down, front/back, that information is not present in two channel recordings. You can create an illusion of depth and height - not the same thing. Now, I have observed that reflecting a part of the sound from room surfaces can cause an image shift toward the reflecting surfaces. This has a twofold perceptual impact. One, it causes the sound to go outside the speaker boxes and appear as an aerial image somewhat behind the plane of the speakers, seeming like the instruments are right there in the room with you, rather than coming from speakers. And I have noticed that this sounds contrived, oversized, diffuse, and not at all realistic. It is, inarguably, inaccurate since the new spatial distribution of the reproduction cannot possibly be anywhere close to the actual event. Secondly, it causes an impression of spaciousness in recordings that contain such information, such as correctly miked symphonies in a good hall. Most of us have experienced this very audible difference between directional speakers and more omni type speakers. Yes, we have. Some of us think that's realism, some of us don't. OK, fine, now between those two types of sound, one is likely to sound closer to live than the other. If you think that is just a preference and worth no further study, then that is the bed you shall l ie in. Taking umbrage at a strawman of your construction is hardly helpful. If I think this is a significant point and worth further study, and try to get others to notice these effects and help me out, then please don't tell me it is all pointless because you are not interested. Yet another strawman. Please provide a quote that even intimates any such thought. As I've said, ad nauseum, and as you've ignored rather perniciously, is that you are ignoring the role of preference, and want to divorce it from the process. Ignoring preference is as egregious an error as ignoring the physics or engineering involved. Audiophiles have been trying to figure out what causes these effects for decades. They have complained about boxy sounding speakers and the hole in the middle effect and wondered what makes some systems sound more realistic than others. And where are all these audiophiles complaining about "hole in the middle"? I've counted exactly one...you. My theories answer some very basic questions about very audible effects, and should be studied further. Yes, more psychoacoustic investigation is called for, to test these effects of reflected sound w respect to the playback situation. No, I have not and cannot do it all on my own. But I need some of those who can do it to pay attention and see if some of my suggestions on speaker placement and radiation patterns and room treatment could be true, so that it might help engineer the installation of stereo systems and the development of new speakers and maybe recording techniques. So, you have an epiphany that tells you those of use who prefer direct radiating speakers are nuts, and reflected sound is the only way to have realism, BUT you need other people to invest time, money, and energy into exploring *if* you *may* be right about said epiphany? And, please, explain why you continue to avoid my simple direct question about whether if you and I disagree about a system being realistic, is one of us wrong? Could it be that you know full well that either way you answer requires that you accept that individual preference is a prime factor? And that, further, there can be no "paradigm" that explains the whole theory of "correct" stereo reproduction unless you exclude preference as a variable? Not *the* variable as you attempt to claim, but a major variable. Keith |
#7
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On 6/11/2012 4:52 PM, Audio Empire wrote:
On Mon, 11 Jun 2012 06:07:29 -0700, Gary Eickmeier wrote (in ): wrote in message ... On 6/9/2012 2:09 PM, Gary Eickmeier wrote: snip You both forgot phase differences. What feature of phase difference cannot be characterized as "temporal" difference? Keith |
#8
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"KH" wrote in message
... So, you have an epiphany that tells you those of use who prefer direct radiating speakers are nuts, and reflected sound is the only way to have realism, BUT you need other people to invest time, money, and energy into exploring *if* you *may* be right about said epiphany? I used no such terms. I explained the perceptual effects and correlated them to radiation pattern etc. And, please, explain why you continue to avoid my simple direct question about whether if you and I disagree about a system being realistic, is one of us wrong? Could it be that you know full well that either way you answer requires that you accept that individual preference is a prime factor? And that, further, there can be no "paradigm" that explains the whole theory of "correct" stereo reproduction unless you exclude preference as a variable? Not *the* variable as you attempt to claim, but a major variable. Keith, Floyd Toole's entire career has been devoted to a series of studies on listener preferences in various loudspeaker and rooms tests. The assumption is that the more preferable speakers have some qualities that are more correct w respect to reproduction. His big story is that a smooth, wide radiation pattern is preferred to a more directional speaker. I had a few arguments with him (as have others) that he hasn't gone far enough into the world of various speaker types, testing mainly direct firing speakers such as those that Harman made. Nevertheless, the principle is the same - the only way we can test for sound reproduction is what we call preference testing, comparing two examples that vary by just one factor, then asking a lot of people which they prefer, and then inferring something about speaker design from that. This is essentially what I have been doing on an anecdotal basis for the last 30 years, after I discovered somthing very significant about speaker positioning. You say you have never heard of the hole in the middle effect, except from me. That doesn't put you in a very good light, knowledge wise. You say maybe you prefer a boxy sound, or that some people may prefer directional speakers, and that sounds more like live to you. OK, fine. Dave Moran calls it the "honking" effect, where the high frequencies narrow in their radiation pattern as FR goes up. Sieffried Linkwitz asked the musical question straight out, which radiation pattern, speaker positioning, and room treatments lead to greater realism in the reproduction. I have been studying these factors for a long time, and have given my anwers and a theory on why it works that way. If you say it is no more than a preference one way or another, then fine, but you would have to try it first to see just what that preference might be, wouldn't you? That is how it is done. Suggest a variable, put it to a listening test, see if there is a definite preference, and figure out what is going on with the physics and press on, hopefully arriving at some asymptotic curve that tells us something about stereo theory. I am bellering from my soapbox because very few researchers would think of trying a negative directivity speaker, nor would they know just how to position them in the room, and even fewer would think of trying specular reflectivity at the front of that room. All of "The Big Three" must be correct in order to perceive the improvement and discover what I have about these factors. They have been doing it by cut and try and happy accident all these years and still not stumbled upon IMT, so here I am. Bose tried the negative directivity index speaker, but screwed up speaker positioning and got in a lawsuit with Consumers Union over the hole in the middle effect. Made the situation even worse, so people wrote all that research off. Mark Davis did an amazing experiment on time/intensity trading to develop the Soundfield One speaker, but failed to try the rear and side reflected portion to complete the picture. Magneplanar developed a great ribbon tweeter that is very omnidirectional, but has equal output front and rear. Still too hot on the direct sound. Same for MBL - they got the equi-omni frequency response really good, but don't say much about positioning or room treatment. A man named Jeffrey Borish invented a system and wrote a paper about deploying additional speakers up front, to the sides of the main speakers, on time delay, to simulate the early reflected sound from the concert hall. He used a description of the image model of live sound to explain why he was doing that. I had lunch with him at one fine AES, and explained that simply reflecting part of the speaker output from your room's walls accomplished the same thing, only more naturally, but he didn't buy it. So I get my big chance and enter the Linkwitz Challenge with my cheap mockup speakers and win, because my speakers are "on theory." Yes, the win was based on a preference, a preference that my speakers sounded more like live sound. It's a whole deal. Gary Eickmeier |
#9
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KH wrote:
On 6/9/2012 2:09 PM, Gary Eickmeier wrote: [...] Stereo has nothing to do with HRTF. As has been stated repeatedly. You asked "where did the recorded ambiance go?". The answer is that the "ambience" is related directly to the HRTF of the listener in the venue. Sans listener, there is *ONLY* temporal and level data available for recording, and when recorded as such, this data cannot subsequently be used to accurately reproduce incident angle information. That information is lost in the translation. That is a binaural, or head-related, process. With stereo, a field-type system, we are reproducing the object itself in front of us and using our own natural hearing mechanism and HRTF to listen to it. Yes, that is the problem. The signal presented to the listener, in the venue, has angular, temporal, and level clues that, And phase as Audio Empire points out. in conjunction with the HRTF of the listener, create a spacial image. That information was not, however, encoded into the recording except as temporal and level information. And possibly phase as well. No matter how that information is played back, the signal reaching the listener cannot be the same as in the venue. It will never be the same, but that's not the point. The point is similar enough. Reflecting the sound cannot, except in the context of listener preference, ameliorate this constraint. It's not staright out prooven either way. But I'd say it's rather improbable. But I'm open to be shown otherwise. That's why I wanted to see a theory not a nice trick. Theory which would explain that the needed clues are in the reproduced signal and distractions are either masked or attenuated enough. snip OK, here comes my main point of this whole discussion, my "closer." We have discussed all of the audible parts of the listening experience in the EEFs, What Can We Hear. We said that the spatial part is the main stumbling block, the main difference between the reproduction and the real thing. Think of it as pure physics. Feel free to present some, please. If the spatial qualities I discussed are audible, then we must make some attempt to reproduce them. We can't reproduce them, they are not on the recording. What we can do is to produce an illusion, the efficacy of which is clearly a function of both engineering efficacy and listener preference. Yes and no. It could be like Imax-3D -- it's illusion and in fact a simplistic one -- but majority of people, those with proper binocular vision perceive the effect. The "real thing" comes to us as a primarily reverberant field from a multiplicity of incident angles. No, it does not, except in a narrow subset of live events. Oh, in fact it does. In majority of live events it does. You got it wrong. In your typical concert hall critical distance is about 4m-5m. In clubs and similar small venues it's even closer. That means that even while one is sitting in a first row the sound of further away instruments is dominated by reverberant sound. Many times the direct component (lets think of outside live events for example, shall we?) Outside events are allmost allways reinforced. So there goes that 'natural' soundstage. is the dominant component, and sometimes by wide margins. Its very rare situation it's a dominant component and virtually never by a wide margin. [...] and if the recording really does contain some of the early reflected sound from the venue, It does contain it; translated into TEMPORAL and LEVEL information. then it is more correct to reproduce that part of the sound by reflecting it from the similar surfaces in your listening room. You are not reflecting *that part of the sound*, you are reflecting ALL of the sound, and in doing so, you reflect the DIRECT portion of the signal as well. That is clearly inappropriate - it doesn't come to you that way in the venue does it? In fact does. It comes dominated by reverberation. If the spacial is as important as you maintain, then reflecting the direct portion of the signal is at least as egregious an error as ignoring the reverberant part of the signal. This is too simplistic. In fact real properly[*] recorded events are miked at a distance closer than a typical listener is. Moreover mikes are typically high in the air, so they get early reflections primarily just from the floor and not from all the close surroundings of typical listener (as there aren't any up there). Stereo recordings recorderd from a typical listener position do not sound too spectacularily. This is (partly) because that sound is then replayed at listener venue where there are additional reflections (nobody listens in anechoic chamber). So good recording already take into account those additional reflections. Thus additional reflections are often 'unnatural' -- they contain peaks due to room shape and dimensions (the incorporate replay room info), in case of box speakers they are much damped in the highs, etc... Gary's technique aims at getting those reflections right as I understand. But what I miss is a physical and psychoaccoustical model of things, not an analogy to mirrors. So this is not a theory it's just a trick. Theory should point out which additions (due to the whole playback chain -- chain starting at the recording) to the sound are benign and which are not, which help recreate the illusion and which are standing in good illusions way. If for example some class of reflections is benign then we might not care if ther are present or not. Is some are troublesome then we know what should be dealt with. [*] I'm speaking in the context of this thread -- propely here means rendering nice deep audio scene in a listener room. rgds \SK -- "Never underestimate the power of human stupidity" -- L. Lang -- http://www.tajga.org -- (some photos from my travels) |
#10
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On Tue, 12 Jun 2012 04:30:37 -0700, KH wrote
(in article ): On 6/11/2012 4:52 PM, Audio Empire wrote: snip You both forgot phase differences. What feature of phase difference cannot be characterized as "temporal" difference? Keith Not the same thing. Two sounds can arrive at the microphone (or ears) at exactly the same time, and yet one sound can have a different phase relationship to the overall sound field than the other. Temporally, they're alike but the varying phase relationships will add to or subtract from the overall "sound picture". In fact, if you are miking an ensemble with two spaced omnidirectional mikes, the phase difference between left and right channels will actually cause some instruments to "disappear" when you blend the right and left mike feeds to achieve mono. Phase differences are one of the main clues our ears use to determine directionality (the others being temporal - the time delay between between sounds reaching the right and the left ears, and level differences - the difference in volume between a sound reaching the left and right ear. |
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On Tue, 12 Jun 2012 04:07:31 -0700, KH wrote
(in article ): On 6/11/2012 6:07 AM, Gary Eickmeier wrote: wrote in message ... Yes, that is the problem. The signal presented to the listener, in the venue, has angular, temporal, and level clues that, in conjunction with the HRTF of the listener, create a spacial image. That information was not, however, encoded into the recording except as temporal and level information. No matter how that information is played back, the signal reaching the listener cannot be the same as in the venue. Reflecting the sound cannot, except in the context of listener preference, ameliorate this constraint. Keith, I'm not sure what exactly your conceptual problem is, I'm tempted to believe you. Not convinced, but tempted. I would posit, however, the conceptual difficulty appears to be yours. but everyone knows that stereo operates on temporal and level differences between channels. You have noticed how those differences can cause the perception of phantom images between the speakers, right? That spatial information is encoded into the channels by means of temporal and level differences in the signals. Then quit asking questions like "where did the information go?". The spatial information you are describing is left/right - that's it. That information *is* encoded in the signal. Up/down, front/back, that information is not present in two channel recordings. You can create an illusion of depth and height - not the same thing. I can't agree with you 100% here. Not the "stereo is an illusion" part. That is certainly true enough, but the part about up/down, front/back, I have to take serious issue with. I have been making true stereo recordings of ensembles of all sizes and types, from small, jazz ensembles to large wind ensembles (concert bands) to full symphony orchestras for many years and I always use some kind of stereo pair. I either use A-B, X-Y, a coincident pair or a single stereo mike in M-S mode. All of my recordings have image height, and front-to-back layering of instruments. How, you ask? It's simple, true stereo is phase coherent. It properly captures the phase relationships between two closely-spaced microphones that tells the listener (on playback, through speakers) that one sound is emanating from in front of or from behind another. It can also tell via these phase cues that, for instance, the brass are up in risers and the woodwinds are at stage level. Also, in a true stereo recording the triangle in the percussion section "seems" to hover over that section just as it does in a real concert hall situation. These aren't anomalies or "illusions" as in trickery, these are repeatable phenomenon that take advantage of the phase coherent nature of true stereo recordings and is well covered by papers from Alan Blumlein et al. Now, I have observed that reflecting a part of the sound from room surfaces can cause an image shift toward the reflecting surfaces. This has a twofold perceptual impact. One, it causes the sound to go outside the speaker boxes and appear as an aerial image somewhat behind the plane of the speakers, seeming like the instruments are right there in the room with you, rather than coming from speakers. And I have noticed that this sounds contrived, oversized, diffuse, and not at all realistic. It is, inarguably, inaccurate since the new spatial distribution of the reproduction cannot possibly be anywhere close to the actual event. This type of "slap" reflection that Mr. Eickmeier refers to tells me that his listening room is way too live. It looks to me like he needs to add some acoustic padding at strategic locations to knock-down this type of room interaction. Secondly, it causes an impression of spaciousness in recordings that contain such information, such as correctly miked symphonies in a good hall. Most of us have experienced this very audible difference between directional speakers and more omni type speakers. Yes, we have. Some of us think that's realism, some of us don't. OK, fine, now between those two types of sound, one is likely to sound closer to live than the other. If you think that is just a preference and worth no further study, then that is the bed you shall l ie in. Taking umbrage at a strawman of your construction is hardly helpful. If I think this is a significant point and worth further study, and try to get others to notice these effects and help me out, then please don't tell me it is all pointless because you are not interested. Yet another strawman. Please provide a quote that even intimates any such thought. As I've said, ad nauseum, and as you've ignored rather perniciously, is that you are ignoring the role of preference, and want to divorce it from the process. Ignoring preference is as egregious an error as ignoring the physics or engineering involved. Especially since the BEST we can do is so far from reality. Audiophiles tend to gravitate to some smaller part of the whole enchilada and obsess over it to try to get it right - often at the expense of other parts of the complete picture. This is 100% preference. One listener obsesses over imaging and uses small book-shelf speakers on stands because they image best, while ignoring the fact that such speakers are often deficient in bass. Another listener requires that the midrange be right, and the rest of the spectrum be damned. Still another might be a bass freak with huge sub-woofers that pressurize his listening room in what he sees as a realistic manner. To pretend that these choices that disparate audiophiles make aren't personal preferences, is, at the very least, an arrogant approach to the question. Were it a question of one speaker system designed according to the precepts of one man (such as our Mr. Eickmeier, here) then there wouldn't be thousands of different models and designs of speakers available. Audiophiles have been trying to figure out what causes these effects for decades. They have complained about boxy sounding speakers and the hole in the middle effect and wondered what makes some systems sound more realistic than others. And where are all these audiophiles complaining about "hole in the middle"? I've counted exactly one...you. Hole in the middle? Then your speakers are too far apart. Put them closer together until the "hole-in-the-middle" disappears. Easy. |
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On 6/12/2012 8:20 PM, Sebastian Kaliszewski wrote:
KH wrote: On 6/9/2012 2:09 PM, Gary Eickmeier wrote: [...] Stereo has nothing to do with HRTF. snip Yes, that is the problem. The signal presented to the listener, in the venue, has angular, temporal, and level clues that, And phase as Audio Empire points out. Well yes, but what is phase except a temporal shift? in conjunction with the HRTF of the listener, create a spacial image. That information was not, however, encoded into the recording except as temporal and level information. And possibly phase as well. Ditto No matter how that information is played back, the signal reaching the listener cannot be the same as in the venue. It will never be the same, but that's not the point. The point is similar enough. Well, no, the point is it still must be an illusion, because the information is not in the recording. I agree, it only need be "sufficient" to fool the listener. But it simply cannot be "the same". Reflecting the sound cannot, except in the context of listener preference, ameliorate this constraint. It's not staright out prooven either way. But I'd say it's rather improbable. But I'm open to be shown otherwise. That's why I wanted to see a theory not a nice trick. Theory which would explain that the needed clues are in the reproduced signal and distractions are either masked or attenuated enough. All subject to individual listener response however. Since the reproduction *must* be different, and must present a different HRTF than the original, it has to be listener dependent. Can you create a model that is statistically "better"? Certainly. But then, you must understand, that statistically, *low* bit-rate MP3's are sonically fine. Therein lies the rub. snip We can't reproduce them, they are not on the recording. What we can do is to produce an illusion, the efficacy of which is clearly a function of both engineering efficacy and listener preference. Yes and no. It could be like Imax-3D -- it's illusion and in fact a simplistic one -- but majority of people, those with proper binocular vision perceive the effect. The "effect", yes. They do not, howefver The "real thing" comes to us as a primarily reverberant field from a multiplicity of incident angles. No, it does not, except in a narrow subset of live events. Oh, in fact it does. In majority of live events it does. You got it wrong. In your typical concert hall critical distance is about 4m-5m. In clubs and similar small venues it's even closer. That means that even while one is sitting in a first row the sound of further away instruments is dominated by reverberant sound. I'm not thinking orchestra, I'm thinking small acoustic groups, in small settings. Oftentimes 10 feet or less. Many times the direct component (lets think of outside live events for example, shall we?) Outside events are allmost allways reinforced. So there goes that 'natural' soundstage. Realism is not confined to non-reinforced music. is the dominant component, and sometimes by wide margins. Its very rare situation it's a dominant component and virtually never by a wide margin. In any amplified outdoor event, it certainly is. snip If the spacial is as important as you maintain, then reflecting the direct portion of the signal is at least as egregious an error as ignoring the reverberant part of the signal. This is too simplistic. I fail to see how, and your description below does not explain it sufficiently, to my mind. In fact real properly[*] recorded events are miked at a distance closer than a typical listener is. Moreover mikes are typically high in the air, so they get early reflections primarily just from the floor and not from all the close surroundings of typical listener (as there aren't any up there). Yes, and how does reflecting these floor reflections - that arrive at the listener from a specific incident angle - from a totally different incident angle, during replay, provide an accurate representation? Stereo recordings recorderd from a typical listener position do not sound too spectacularily. This is (partly) because that sound is then replayed at listener venue where there are additional reflections (nobody listens in anechoic chamber). So good recording already take into account those additional reflections. Thus additional reflections are often 'unnatural' -- they contain peaks due to room shape and dimensions (the incorporate replay room info), in case of box speakers they are much damped in the highs, etc... I would basically agree. But, "taking into account those additional reflections" means altering the recording to account for the playback medium and venue. Such tailoring must make the information on the recording inaccurate relative to the acoustic in the original venue, no? Almost analogous to an RIAA pre-emphasis and de-emphasis without a reference standard. Keith |
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On 6/12/2012 7:09 PM, Gary Eickmeier wrote:
wrote in message ... So, you have an epiphany that tells you those of use who prefer direct radiating speakers are nuts, and reflected sound is the only way to have realism, BUT you need other people to invest time, money, and energy into exploring *if* you *may* be right about said epiphany? I used no such terms. I explained the perceptual effects and correlated them to radiation pattern etc. No, the description is mine. You've provided no counterpoint to my interpretation, however. And, please, explain why you continue to avoid my simple direct question about whether if you and I disagree about a system being realistic, is one of us wrong? Could it be that you know full well that either way you answer requires that you accept that individual preference is a prime factor? And that, further, there can be no "paradigm" that explains the whole theory of "correct" stereo reproduction unless you exclude preference as a variable? Not *the* variable as you attempt to claim, but a major variable. Keith, Floyd Toole's entire career has been devoted to a series of studies on listener preferences in various loudspeaker and rooms tests. The assumption is that the more preferable speakers have some qualities that are more correct w respect to reproduction. Did I ask about Floyd Toole? No, I asked you a direct question and you you dodge, weave, obfuscate, and refuse to answer. Why? Never mind, I know why. snip This is essentially what I have been doing on an anecdotal basis for the last 30 years, after I discovered somthing very significant about speaker positioning. In your opinion. You say you have never heard of the hole in the middle effect, except from me. That doesn't put you in a very good light, knowledge wise. It puts you in a far worse light integrity-wise. You claimed that audiophiles have complained for decades about this problem. I relayed that I have not heard such complaints from any audiophiles except you. Please quote anyone else in this group who has complained about this issue. You say maybe you prefer a boxy sound, That, is a crock. You are being disingenuous and you know it. I have taken great pains to disabuse you of such misperceptions yet you persist. or that some people may prefer directional speakers, and that sounds more like live to you. OK, fine. Dave Moran calls it the "honking" effect, where the high frequencies narrow in their radiation pattern as FR goes up. And the relevance would be? Dave Moran is an arbiter of my preferences and perceptions based upon...? Sieffried Linkwitz asked the musical question straight out, which radiation pattern, speaker positioning, and room treatments lead to greater realism in the reproduction. I have been studying these factors for a long time, and have given my anwers and a theory on why it works that way. Yes you have. And we've debated that theory, only to have you become more bellicose and confrontational as others have failed to accept your theory, sans evidence or supporting theoretical construct. This is not an effective means of persuasion. If you say it is no more than a preference one way or another, You know what, Gary, it is clear you are going to continue to misrepresent what others (at least I) say, repeatedly, no matter how often you are corrected, and no matter how clear and unambiguous those corrections are. You are not arguing a theory, you are pursuing a pogrom. Since you refuse to pursue a forthright discussion, I'll devote no more time to it. Keith |
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On 6/12/2012 8:24 PM, Audio Empire wrote:
On Tue, 12 Jun 2012 04:07:31 -0700, KH wrote (in ): On 6/11/2012 6:07 AM, Gary Eickmeier wrote: wrote in message ... snip Then quit asking questions like "where did the information go?". The spatial information you are describing is left/right - that's it. That information *is* encoded in the signal. Up/down, front/back, that information is not present in two channel recordings. You can create an illusion of depth and height - not the same thing. I can't agree with you 100% here. Not the "stereo is an illusion" part. That is certainly true enough, but the part about up/down, front/back, I have to take serious issue with. What part of the signal codes for these spatial effects that are not temporal or level in nature? What am I missing? Clearly, speaker radiation patterns are designed to present this illusion, but as far as I can tell, it is illusory relative to the recorded signal. Left/right data is directly addressable since you have one speaker per channel. I have been making true stereo recordings of ensembles of all sizes and types, from small, jazz ensembles to large wind ensembles (concert bands) to full symphony orchestras for many years and I always use some kind of stereo pair. I either use A-B, X-Y, a coincident pair or a single stereo mike in M-S mode. All of my recordings have image height, and front-to-back layering of instruments. How, you ask? It's simple, true stereo is phase coherent. It properly captures the phase relationships between two closely-spaced microphones that tells the listener (on playback, through speakers) that one sound is emanating from in front of or from behind another. It can also tell via these phase cues that, for instance, the brass are up in risers and the woodwinds are at stage level. Also, in a true stereo recording the triangle in the percussion section "seems" to hover over that section just as it does in a real concert hall situation. These aren't anomalies or "illusions" as in trickery, these are repeatable phenomenon that take advantage of the phase coherent nature of true stereo recordings and is well covered by papers from Alan Blumlein et al. Yes, but phase differences are simply temporal differences. Perhaps I should've been clearer in my usage. I'm not suggesting that phase differences cannot be used to convey some spatial information, only that speaker radiation patterns must 'mimic' the source sufficiently to fool our hearing. The depth and height is not really there, in a discreet sense as is left/right information, front/back/high/low frequency "A" comes from the same point - thus placement of such signals across a soundstage is an illusion. Not "trickery", just making use of how we interpret sound. And many, many illusions are repeatable (visual as well as auditory). And you can certainly mess that up during replay. Take a couple of sine waves, out of phase by some degree, and purposely bounce them off a wall such that the phase relationship changes. How is that accurate, or helpful, or realistic? snip Ignoring preference is as egregious an error as ignoring the physics or engineering involved. Especially since the BEST we can do is so far from reality. Audiophiles tend to gravitate to some smaller part of the whole enchilada and obsess over it to try to get it right - often at the expense of other parts of the complete picture. This is 100% preference. One listener obsesses over imaging and uses small book-shelf speakers on stands because they image best, while ignoring the fact that such speakers are often deficient in bass. Another listener requires that the midrange be right, and the rest of the spectrum be damned. Still another might be a bass freak with huge sub-woofers that pressurize his listening room in what he sees as a realistic manner. To pretend that these choices that disparate audiophiles make aren't personal preferences, is, at the very least, an arrogant approach to the question. Were it a question of one speaker system designed according to the precepts of one man (such as our Mr. Eickmeier, here) then there wouldn't be thousands of different models and designs of speakers available. Agreed, although Mr. Eickmeier sees the plethora of speaker designs as clear evidence that "no one knows" what's going on, thus some "unified theory" is needed. snip And where are all these audiophiles complaining about "hole in the middle"? I've counted exactly one...you. Hole in the middle? Then your speakers are too far apart. Put them closer together until the "hole-in-the-middle" disappears. Easy. Kind of my point. I don't hear people complaining about this "problem" unless they know nothing about speaker placement. Keith |
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KH wrote:
On 6/12/2012 8:20 PM, Sebastian Kaliszewski wrote: KH wrote: On 6/9/2012 2:09 PM, Gary Eickmeier wrote: [...] Stereo has nothing to do with HRTF. snip Yes, that is the problem. The signal presented to the listener, in the venue, has angular, temporal, and level clues that, And phase as Audio Empire points out. Well yes, but what is phase except a temporal shift? You're conflating phase and wavefront. You can have 180deg off phase signals coming at the same moment. in conjunction with the HRTF of the listener, create a spacial image. That information was not, however, encoded into the recording except as temporal and level information. And possibly phase as well. Ditto See above. Phase is a property different from timing. No matter how that information is played back, the signal reaching the listener cannot be the same as in the venue. It will never be the same, but that's not the point. The point is similar enough. Well, no, the point is it still must be an illusion, because the information is not in the recording. PArt of the infomation is. You're making an error 180deg from Gary's error, but stil an error. Due to projection from higher to lower number of dimansions part of the information is lost but part is still retained. I agree, it only need be "sufficient" to fool the listener. But it simply cannot be "the same". But "the same" is not needed. Our ears have finite resolution and our brains are sesnsitive obly to some parts of the signal. Reflecting the sound cannot, except in the context of listener preference, ameliorate this constraint. It's not staright out prooven either way. But I'd say it's rather improbable. But I'm open to be shown otherwise. That's why I wanted to see a theory not a nice trick. Theory which would explain that the needed clues are in the reproduced signal and distractions are either masked or attenuated enough. All subject to individual listener response however. Since the reproduction *must* be different, and must present a different HRTF than the original, it has to be listener dependent. Only to a point. Listeners are humans not superbeings and all have their limitations. If you have an device capable of running 30Mph you can outrun any human going on his feet. IOW listener dependence has its bounds. Can you create a model that is statistically "better"? Certainly. But then, you must understand, that statistically, *low* bit-rate MP3's are sonically fine. And high bitrate Oggs, Musepacks or AC3s are sonically indistinguishable. [...] The "real thing" comes to us as a primarily reverberant field from a multiplicity of incident angles. No, it does not, except in a narrow subset of live events. Oh, in fact it does. In majority of live events it does. You got it wrong. In your typical concert hall critical distance is about 4m-5m. In clubs and similar small venues it's even closer. That means that even while one is sitting in a first row the sound of further away instruments is dominated by reverberant sound. I'm not thinking orchestra, I'm thinking small acoustic groups, in small settings. Oftentimes 10 feet or less. In small venues critical distance is also small. Many times the direct component (lets think of outside live events for example, shall we?) Outside events are allmost allways reinforced. So there goes that 'natural' soundstage. Realism is not confined to non-reinforced music. But in case of reinforced music you don't have an natural audio scene to capture. is the dominant component, and sometimes by wide margins. Its very rare situation it's a dominant component and virtually never by a wide margin. In any amplified outdoor event, it certainly is. Ditto. Besides those are most typically recorded by taping electical signals before the go into PA reinforcement system. Any auditory scene is then created in porstprocessing. If the spacial is as important as you maintain, then reflecting the direct portion of the signal is at least as egregious an error as ignoring the reverberant part of the signal. This is too simplistic. I fail to see how, and your description below does not explain it sufficiently, to my mind. In fact real properly[*] recorded events are miked at a distance closer than a typical listener is. Moreover mikes are typically high in the air, so they get early reflections primarily just from the floor and not from all the close surroundings of typical listener (as there aren't any up there). Yes, and how does reflecting these floor reflections - that arrive at the listener from a specific incident angle - from a totally different incident angle, during replay, provide an accurate representation? First, one have to ascertain what acuracy of incident angles is really needed. That's in fact a part of what I miss from what Gary presented. Second, those floor reflections in real life listener position (i.e. not 10 feet allmost above conductors head) get rereflected as well. Stereo recordings recorderd from a typical listener position do not sound too spectacularily. This is (partly) because that sound is then replayed at listener venue where there are additional reflections (nobody listens in anechoic chamber). So good recording already take into account those additional reflections. Thus additional reflections are often 'unnatural' -- they contain peaks due to room shape and dimensions (the incorporate replay room info), in case of box speakers they are much damped in the highs, etc... I would basically agree. But, "taking into account those additional reflections" means altering the recording to account for the playback medium and venue. Such tailoring must make the information on the recording inaccurate relative to the acoustic in the original venue, no? Well, this information is accurate at the miking position(s). Only that position is choosen Almost analogous to an RIAA pre-emphasis and de-emphasis without a reference standard. Somewhat, I agree. But even without pre-emphasis standard no preemphasis at all was worse. Similarily, recordings miked from typical listener position tend to present unimpressive audio scene rendidtion. If someone came with good theory allowing us convicing audio scene recreation without sacrificing other audio aspects some standard like -- place mikes always 12ft above flooor, pointed such as such, etc. rgds \SK -- "Never underestimate the power of human stupidity" -- L. Lang -- http://www.tajga.org -- (some photos from my travels) |
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On Wed, 13 Jun 2012 05:55:18 -0700, KH wrote
(in article ): On 6/12/2012 8:24 PM, Audio Empire wrote: On Tue, 12 Jun 2012 04:07:31 -0700, KH wrote (in ): On 6/11/2012 6:07 AM, Gary Eickmeier wrote: wrote in message ... snip Then quit asking questions like "where did the information go?". The spatial information you are describing is left/right - that's it. That information *is* encoded in the signal. Up/down, front/back, that information is not present in two channel recordings. You can create an illusion of depth and height - not the same thing. I can't agree with you 100% here. Not the "stereo is an illusion" part. That is certainly true enough, but the part about up/down, front/back, I have to take serious issue with. What part of the signal codes for these spatial effects that are not temporal or level in nature? What am I missing? Phase differences! They are critical to that perception. Clearly, speaker radiation patterns are designed to present this illusion, but as far as I can tell, it is illusory relative to the recorded signal. Left/right data is directly addressable since you have one speaker per channel. I have been making true stereo recordings of ensembles of all sizes and types, from small, jazz ensembles to large wind ensembles (concert bands) to full symphony orchestras for many years and I always use some kind of stereo pair. I either use A-B, X-Y, a coincident pair or a single stereo mike in M-S mode. All of my recordings have image height, and front-to-back layering of instruments. How, you ask? It's simple, true stereo is phase coherent. It properly captures the phase relationships between two closely-spaced microphones that tells the listener (on playback, through speakers) that one sound is emanating from in front of or from behind another. It can also tell via these phase cues that, for instance, the brass are up in risers and the woodwinds are at stage level. Also, in a true stereo recording the triangle in the percussion section "seems" to hover over that section just as it does in a real concert hall situation. These aren't anomalies or "illusions" as in trickery, these are repeatable phenomenon that take advantage of the phase coherent nature of true stereo recordings and is well covered by papers from Alan Blumlein et al. Yes, but phase differences are simply temporal differences. AS I have explained before, they are not temporal in that many different phases that make up a wavefront can all arrive at the microphone diaphragm (or the listener's ears) at EXACTLY the same time and yet be different enough for the ear to reconstruct from the different phases entering the room from the speakers a three-dimensional aural image containing width, depth, and height cues. Perhaps I should've been clearer in my usage. I'm not suggesting that phase differences cannot be used to convey some spatial information, only that speaker radiation patterns must 'mimic' the source sufficiently to fool our hearing. The depth and height is not really there, in a discreet sense as is left/right information, front/back/high/low frequency "A" comes from the same point - thus placement of such signals across a soundstage is an illusion. OK, I buy that. Yes, it is conveyed into our room as strictly a left and a right component. It takes both components, merging in the air in the room between the speaker diaphragm and one's ears to recreate a three-dimensional sound field. Our ears do the interpretation of what these phase differences actually mean. It's the brain that hears "within" that soundfield, phase differences between the right channel signal and the same information in the left channel and from those cues constructs the "illusion" that this instrument is further back than that instrument or that this instrument is playing from a position higher than that instrument. The info is all there UNLESS the microphones are too far apart. In that case, I suspect the time delay between the arriving phase variations from any given instrument or group of instruments is too long for the ear to properly reconstruct pin-point depth and height info. That has been my experience, anyway. I admit that I'm guessing at why spaced omnis don't image as well as a real stereo pair, but there it is. Not "trickery", just making use of how we interpret sound. And many, many illusions are repeatable (visual as well as auditory). And you can certainly mess that up during replay. Take a couple of sine waves, out of phase by some degree, and purposely bounce them off a wall such that the phase relationship changes. How is that accurate, or helpful, or realistic? snip Ignoring preference is as egregious an error as ignoring the physics or engineering involved. Especially since the BEST we can do is so far from reality. Audiophiles tend to gravitate to some smaller part of the whole enchilada and obsess over it to try to get it right - often at the expense of other parts of the complete picture. This is 100% preference. One listener obsesses over imaging and uses small book-shelf speakers on stands because they image best, while ignoring the fact that such speakers are often deficient in bass. Another listener requires that the midrange be right, and the rest of the spectrum be damned. Still another might be a bass freak with huge sub-woofers that pressurize his listening room in what he sees as a realistic manner. To pretend that these choices that disparate audiophiles make aren't personal preferences, is, at the very least, an arrogant approach to the question. Were it a question of one speaker system designed according to the precepts of one man (such as our Mr. Eickmeier, here) then there wouldn't be thousands of different models and designs of speakers available. Agreed, although Mr. Eickmeier sees the plethora of speaker designs as clear evidence that "no one knows" what's going on, thus some "unified theory" is needed. That's where he errs. There is no "Unified Theory" simply because no speaker is perfect, or even close to perfect, so each maker is going off looking for the ideal "his piece of the puzzle". If perfect speakers existed, there would be no need for these disparate design methodologies. One speaker design and one design only would suffice. I don't see why Mr Eickmeier has so much trouble with that concept. snip And where are all these audiophiles complaining about "hole in the middle"? I've counted exactly one...you. Hole in the middle? Then your speakers are too far apart. Put them closer together until the "hole-in-the-middle" disappears. Easy. Kind of my point. I don't hear people complaining about this "problem" unless they know nothing about speaker placement. Exactly! Keith |
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On=20Wed=20Jun=2013=2023:47:10=202012=20Sebastian= 20Kaliszewski=20=
=20wrote: =20If=20someone=20came=20with=20good=20theory=20a llowing=20us=20c= onvicing=20audio=20scene=20recreation =20without=20sacrificing=20other=20audio=20aspect s=20some=20stand= ard=20like=20--=20place=20mikes=20always =2012ft=20above=20flooor,=20pointed=20such=20as=2 0such,=20etc. Hi=20Sebastian=20- Welcome=20to=20the=20dogfight! I=20was=20just=20trying=20to=20relate=20a=20subjec t=20that=20has= =20been=20near=20and=20dear=20to=20my=20heart=20fo r=20a=20long=20t= ime,=20and=20it=20has=20turned=20into=20a=20Hatfie lds=20and=20McCo= ys=20pitched=20battle=20for=20some=20reason.=20I=2 0think=20audio= =20people=20have=20a=20lot=20of=20dug=20in=20ideas =20that=20are=20= hard=20to=20change.=20There=20is=20also=20a=20lot= 20of=20miscommun= ication=20here,=20sometimes=20because=20we=20don't =20try=20very=20= hard=20to=20understand=20the=20other's=20point.=20 In=20any=20case= =20I=20didn't=20intend=20it=20to=20turn=20out=20th is=20way=20-=20j= ust=20wanted=20to=20run=20a=20few=20ideas=20up=20t he=20flagpole=20= in=20a=20friendly=20manner=20and=20use=20the=20sim ple=20to=20compl= ex=20method=20to=20do=20that.=20Start=20with=20a=2 0few=20things=20= that=20we=20would=20all=20agree=20on,=20then=20rat chet=20it=20up= =20to=20some=20things=20that=20I=20have=20discover ed. In=20order=20to=20do=20your=20convincing=20audio=2 0scene=20recreat= ion=20we=20first=20study=20What=20Can=20We=20Hear, =20by=20means=20= of=20describing=20all=20of=20the=20MAJOR=20categor ies,=20or=20aspe= cts,=20of=20sound=20that=20are=20audible=20and=20r elate=20them=20t= o=20the=20repro=20problem.=20We=20got=20down=20to= 20the=20spatial= =20characteristics=20as=20being=20the=20main=20stu mbling=20block,= =20and=20the=20new=20paradigm=20that=20I=20attempt ed=20to=20relate= =20as=20a=20way=20of=20looking=20at=20the=20proble m=20is=20the=20w= ell-known=20technique=20of=20image=20modeling.=20It=20 is=20just=20= a=20more=20visual=20way=20of=20studying=20the=20di rect=20and=20ear= ly=20reflected=20parts=20of=20the=20sound=20fields .=20If=20you=20t= ake=20a=20look=20at=20the=20image=20model=20of=20r eproduced=20soun= d=20from=20speakers,=20you=20can=20compare=20that= 20to=20the=20liv= e=20model=20and=20see=20the=20differences.=20There =20are=20obvious= =20physical=20differences=20in=20the=20"shape"=20o f=20these=20fiel= ds=20that=20we=20can=20make=20a=20little=20better= 20with=20what=20= I=20call=20The=20Big=20Three=20-=20speaker=20positioning,=20radiat= ion=20pattern,=20and=20room=20acoustics.=20This=20 is=20possible=20= because=20the=20two=20rooms,=20although=20differen t=20sizes,=20are= =20geometrically=20similar. Maybe=20I=20should=20quit=20while=20I=20am=20behin d=20-=20and=20yo= u=20can=20read=20thru=20the=20thread=20-=20but=20that=20is=20basic= ally=20the=20theory=20that=20you=20are=20asking=20 for.=20Specifica= lly,=20it=20says=20that=20the=20reproduction=20wil l=20sound=20clos= est=20to=20the=20live=20sound=20when=20the=20image =20model=20of=20= the=20reproduction=20sound=20field=20is=20as=20clo se=20to=20that= =20of=20the=20live=20field=20as=20possible.=20I=20 refer=20to=20all= =20audible=20characteristics=20of=20both=20fields, =20which=20is=20= why=20I=20started=20with=20the=20What=20Can=20We=2 0Hear=20thread= =2E=20To=20me,=20this=20theory=20is=20a=20tautolog y=20-=20an=20ind= isputable=20fact=20that=20is=20so=20obvious=20that =20it=20requires= =20no=20proof.=20To=20others,=20it=20is=20a=20chal lenge=20to=20lon= g=20held=20beliefs. Gary=20Eickmeier |
#18
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Posted to rec.audio.high-end
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On Wed Jun 13 23:47:10 2012 Sebastian Kaliszewski wrote:
If someone came with good theory allowing us convicing audio scene recreation without sacrificing other audio aspects some standard like -- place mikes always 12ft above flooor, pointed such as such, etc. Hi Sebastian - Welcome to the dogfight! I was just trying to relate a subject that has been near and dear to my heart for a long time, and it has turned into a Hatfields and McCoys pitched battle for some reason. I think audio people have a lot of dug in ideas that are hard to change. There is also a lot of miscommunication here, sometimes because we don't try very hard to understand the other's point. In any case I didn't intend it to turn out this way - just wanted to run a few ideas up the flagpole in a friendly manner and use the simple to complex method to do that. Start with a few things that we would all agree on, then ratchet it up to some things that I have discovered. In order to do your convincing audio scene recreation we first study What Can We Hear, by means of describing all of the MAJOR categories, or aspects, of sound that are audible and relate them to the repro problem. We got down to the spatial characteristics as being the main stumbling block, and the new paradigm that I attempted to relate as a way of looking at the problem is the well-known technique of image modeling. It is just a more visual way of studying the direct and early reflected parts of the sound fields. If you take a look at the image model of reproduced sound from speakers, you can compare that to the live model and see the differences. There are obvious physical differences in the "shape" of these fields that we can make a little better with what I call The Big Three - speaker positioning, radiation pattern, and room acoustics. This is possible because the two rooms, although different sizes, are geometrically similar. Maybe I should quit while I am behind - and you can read thru the thread - but that is basically the theory that you are asking for. Specifically, it says that the reproduction will sound closest to the live sound when the image model of the reproduction sound field is as close to that of the live field as possible. I refer to all audible characteristics of both fields, which is why I started with the What Can We Hear thread. To me, this theory is a tautology - an indisputable fact that is so obvious that it requires no proof. To others, it is a challenge to long held beliefs. Gary Eickmeier |
#19
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Posted to rec.audio.high-end
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On Thu, 14 Jun 2012 17:59:41 -0700, Gary Eickmeier wrote
(in article ): On Wed Jun 13 23:47:10 2012 Sebastian Kaliszewski wrote: If someone came with good theory allowing us convicing audio scene recreation without sacrificing other audio aspects some standard like -- place mikes always 12ft above flooor, pointed such as such, etc. Hi Sebastian - Welcome to the dogfight! I was just trying to relate a subject that has been near and dear to my heart for a long time, and it has turned into a Hatfields and McCoys pitched battle for some reason. I think audio people have a lot of dug in ideas that are hard to change. There is also a lot of miscommunication here, sometimes because we don't try very hard to understand the other's point. In any case I didn't intend it to turn out this way - just wanted to run a few ideas up the flagpole in a friendly manner and use the simple to complex method to do that. Start with a few things that we would all agree on, then ratchet it up to some things that I have discovered. It's not a "pitched battle" Gary, it's just that you offered up a "theory" that has no basis in the physics of acoustics or even in the realm of psychoacoustics. Add to that the fact that your theory assumes that everyone is listening in the same way to the same characteristics in various speakers, and of, course, you're going to get people who disagree with you. An analogy would be someone going on a food newsgroup and stating: "I've been eating different foods lately, and I've come to the conclusion that broccoli is the best food there is." Then, after making that statement, expecting everyone to agree with them and becoming upset when they find that many people disagree. The fact is that there are many different aspects of reproduced music that people are drawn to according to their individual tastes. There is no "Unified Speaker Theory" nor can there be until somebody manages to design a speaker that is perfect in every way. Then that technology will be the way to design speakers and everything else can be relegated to history. Of course, such a design, were it even remotely possible, would. likely, of necessity, be very expensive, and other companies (from the one that came up with the perfect speaker) would try to make perfect speakers cheaper. So then they would start to diverge from the "true path". Basically, even if a perfect speaker were invented, designers with other ideas would introduce their own vision of perfection and the whole thing would start anew. In order to do your convincing audio scene recreation we first study What Can We Hear, by means of describing all of the MAJOR categories, or aspects, of sound that are audible and relate them to the repro problem. Even after you identify all of the things that humans can hear (which has been done), physics prevents us from building any contrivances that will get even half of them right. That's why there are so many different approaches to these problems: cone speakers, planar speakers, dipoles, omnidirectional speakers like the German MBLs, Air Motion Transformers, ribbons, the list goes on and on. We got down to the spatial characteristics as being the main stumbling block, and the new paradigm that I attempted to relate as a way of looking at the problem is the well-known technique of image modeling. It is just a more visual way of studying the direct and early reflected parts of the sound fields. If you take a look at the image model of reproduced sound from speakers, you can compare that to the live model and see the differences. There are obvious physical differences in the "shape" of these fields that we can make a little better with what I call The Big Three - speaker positioning, radiation pattern, and room acoustics. This is possible because the two rooms, although different sizes, are geometrically similar. Again, room acoustics for most listening rooms are a tertiary effect at best, and really can't be part of the equation because it is something that the equipment manufacturers have no control over just as they (and the listener) have no control over how the recording that they are playing was made. Maybe I should quit while I am behind - and you can read thru the thread - but that is basically the theory that you are asking for. Specifically, it says that the reproduction will sound closest to the live sound when the image model of the reproduction sound field is as close to that of the live field as possible. There is no argument there. But since that's impossible for a dozen or more reasons that are beyond the control of anyone trying to quantize that theory, it's pretty futile. Not only that, but your notion is nothing new. Audio engineers, acousticians, etc, have known these things for decades, but have realized that without complete control of all parameters, from the source musicians to the listening venue, it's a useless pursuit. I refer to all audible characteristics of both fields, which is why I started with the What Can We Hear thread. To me, this theory is a tautology - an indisputable fact that is so obvious that it requires no proof. To others, it is a challenge to long held beliefs. No it isn't. It's YOUR conclusions that are the challenge, not the basic questions. Nobody here (that I have read) challenge your premise: "...reproduction will sound closest to the live sound when the image model of the reproduction sound field is as close to that of the live field as possible." But everybody challenges your singular vision of how to accomplish this and even the fact that any one solution can possibly even begin to address this issue. I don't think that you purposely twist people's words. but it looks like that sometimes, the way you phrase what you believe to be other people's reactions to your posts. |
#20
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Posted to rec.audio.high-end
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On 6/13/2012 4:47 PM, Sebastian Kaliszewski wrote:
KH wrote: On 6/12/2012 8:20 PM, Sebastian Kaliszewski wrote: KH wrote: snip And phase as Audio Empire points out. Well yes, but what is phase except a temporal shift? You're conflating phase and wavefront. You can have 180deg off phase signals coming at the same moment. What I meant to say was "phase differences". Two identical waves 180deg off phase are different only in an f/2 temporal shift right? in conjunction with the HRTF of the listener, create a spacial image. That information was not, however, encoded into the recording except as temporal and level information. And possibly phase as well. Ditto See above. Phase is a property different from timing. With respect to the specific discussion, I don't see how they can be considered separate properties. For example, if we were to take two instruments that could produce a single pure tone (hypothetically) and place them on a stage, one 3M from the mic, and one 5M from the mic, and shifted laterally 1M. If both instruments were started simultaneously, calibrated to provide equal signal levels at the microphone, then the wavefront at the microphone position would, from a direct perspective, comprise two out of phase waves right? Yet, the only difference in the signals is arrival times of the respective peaks and troughs, no? So add a second microphone, and you have the same signals recorded from a different position in space. As long as you know the microphone positions, its easy to determine the relative positions of the two instruments, aurally or mathematically. Yet when you add in the effects of the reverberant sound field you have a whole new set of signals of varying strengths and arrival times, and thus phase differences. As a listener, in place of the microphones, even minor head movements allow you to localize the instruments by sampling different angular presentations (i.e. the HRTF effect) and analyzing multiple wave fronts. This depth of information is simply not captured in a stereo recording. That is the information that is missing; that's the information that allows us to establish accurate positional data. snip Well, no, the point is it still must be an illusion, because the information is not in the recording. PArt of the infomation is. Part, yes. That's the point. Is there enough to make a pretty convincing reproduction? Clearly yes for a vast number of folks. You're making an error 180deg from Gary's error, but stil an error. Due to projection from higher to lower number of dimansions part of the information is lost but part is still retained. The part that is lost is the part that allows us to "make sense" of the reverberant sound field. Similar to the failings of binaural; the reverberant field is there, but from a single fixed perspective which defeats a lot of our ability to localize sounds as we do normally. I agree, it only need be "sufficient" to fool the listener. But it simply cannot be "the same". But "the same" is not needed. Our ears have finite resolution and our brains are sesnsitive obly to some parts of the signal. Absolutely true. Now, if we were talking about using that information and tailoring the reproduction to accentuate the parts to which are most sensitive (e.g. perceptual coding), no problem. We're not though. We're talking about a brute force approach that adds a lot of spacial information that is not related to the spatial environment of the venue. Hence the whole concept of the reproduction as a "separate work of art". Reflecting the sound cannot, except in the context of listener preference, ameliorate this constraint. It's not staright out prooven either way. But I'd say it's rather improbable. But I'm open to be shown otherwise. That's why I wanted to see a theory not a nice trick. Theory which would explain that the needed clues are in the reproduced signal and distractions are either masked or attenuated enough. I agree that a real theory would be nice. I think, however, that it's pretty clear that taking the entire signal, direct and reverberant, and adding additional phase shifts by reflecting off the front wall, is a totally indiscriminate approach. All subject to individual listener response however. Since the reproduction *must* be different, and must present a different HRTF than the original, it has to be listener dependent. Only to a point. Listeners are humans not superbeings and all have their limitations. I disagree. Listener limitations are the issue. If we were superbeings, and all heard "perfectly", then we could, indeed, create some universally recognized paradigm for perfect reproduction (might not get there physically, but it's theoretically feasible). If you have an device capable of running 30Mph you can outrun any human going on his feet. IOW listener dependence has its bounds. I don't think that's true, in this context. Aural limitations that *I* have are more likely, IMO, to make me prefer a different presentation than a 20 year old with perfect hearing. IOW, I don't think there can be a universal standard of sufficiency, precisely because of listener limitations or preferences. Can you create a model that is statistically "better"? Certainly. But then, you must understand, that statistically, *low* bit-rate MP3's are sonically fine. And high bitrate Oggs, Musepacks or AC3s are sonically indistinguishable. That's not the point though. Even ignoring that there are likely those who would disagree with that characterization. The point is, yes, you can do lot's of things to improve the reproduction, things that may, statistically be considered better - possibly by a large margin - but that does not a "paradigm" make. snip In fact real properly[*] recorded events are miked at a distance closer than a typical listener is. Moreover mikes are typically high in the air, so they get early reflections primarily just from the floor and not from all the close surroundings of typical listener (as there aren't any up there). Yes, and how does reflecting these floor reflections - that arrive at the listener from a specific incident angle - from a totally different incident angle, during replay, provide an accurate representation? First, one have to ascertain what acuracy of incident angles is really needed. That's in fact a part of what I miss from what Gary presented. Yes, but using his approach, it doesn't matter how much accuracy is *needed* because there is no selective filtering of any kind being applied. Second, those floor reflections in real life listener position (i.e. not 10 feet allmost above conductors head) get rereflected as well. Stereo recordings recorderd from a typical listener position do not sound too spectacularily. This is (partly) because that sound is then replayed at listener venue where there are additional reflections (nobody listens in anechoic chamber). So good recording already take into account those additional reflections. Thus additional reflections are often 'unnatural' -- they contain peaks due to room shape and dimensions (the incorporate replay room info), in case of box speakers they are much damped in the highs, etc... I would basically agree. But, "taking into account those additional reflections" means altering the recording to account for the playback medium and venue. Such tailoring must make the information on the recording inaccurate relative to the acoustic in the original venue, no? Well, this information is accurate at the miking position(s). Only that position is choosen OK but then you are not talking about "taking into account" the additional reflections in the context of adjusting the recording to compensate, right? Almost analogous to an RIAA pre-emphasis and de-emphasis without a reference standard. Somewhat, I agree. But even without pre-emphasis standard no preemphasis at all was worse. Similarily, recordings miked from typical listener position tend to present unimpressive audio scene rendidtion. I read your "taking into account" description above as meaning you adjust the recording to compensate, hence my analogy of RIAA. It appears I misunderstood you. Keith |
#21
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Posted to rec.audio.high-end
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On Sun, 17 Jun 2012 12:59:06 -0700, KH wrote
(in article ): On 6/13/2012 4:47 PM, Sebastian Kaliszewski wrote: KH wrote: On 6/12/2012 8:20 PM, Sebastian Kaliszewski wrote: KH wrote: snip And phase as Audio Empire points out. Well yes, but what is phase except a temporal shift? You're conflating phase and wavefront. You can have 180deg off phase signals coming at the same moment. What I meant to say was "phase differences". Two identical waves 180deg off phase are different only in an f/2 temporal shift right? in conjunction with the HRTF of the listener, create a spacial image. That information was not, however, encoded into the recording except as temporal and level information. And possibly phase as well. Ditto See above. Phase is a property different from timing. With respect to the specific discussion, I don't see how they can be considered separate properties. For example, if we were to take two instruments that could produce a single pure tone (hypothetically) and place them on a stage, one 3M from the mic, and one 5M from the mic, and shifted laterally 1M. If both instruments were started simultaneously, calibrated to provide equal signal levels at the microphone, then the wavefront at the microphone position would, from a direct perspective, comprise two out of phase waves right? Yet, the only difference in the signals is arrival times of the respective peaks and troughs, no? Not necessarily. First of all, both players might night start the note in the same place, but start it at the same time meaning that their wavefronts might arrive at the diaphragm at a time shifted by their differences, but might be greater of less than 180 degrees out of phase. Also a real flute waveform is more complex than a simple sinewave, and therefore there will be phase anomalies within the two flutes. Now if we use two speakers fed by a sinewave generator, the problem will still exist that unless it's the same generator through two speakers there will still be a random phase component other than the distance component. But that hardly tells us anything about the real world. So add a second microphone, and you have the same signals recorded from a different position in space. As long as you know the microphone positions, its easy to determine the relative positions of the two instruments, aurally or mathematically. Yet when you add in the effects of the reverberant sound field you have a whole new set of signals of varying strengths and arrival times, and thus phase differences. As a listener, in place of the microphones, even minor head movements allow you to localize the instruments by sampling different angular presentations (i.e. the HRTF effect) and analyzing multiple wave fronts. This depth of information is simply not captured in a stereo recording. Sure it is. It's capture by only two mikes (ideally), but in the right circumstances, that's enough. That is the information that is missing; that's the information that allows us to establish accurate positional data. I maintain that in a properly made recording, it's not missing. |
#22
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Posted to rec.audio.high-end
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On 6/17/2012 6:34 PM, Audio Empire wrote:
On Sun, 17 Jun 2012 12:59:06 -0700, KH wrote (in ): On 6/13/2012 4:47 PM, Sebastian Kaliszewski wrote: KH wrote: On 6/12/2012 8:20 PM, Sebastian Kaliszewski wrote: KH wrote: snip So add a second microphone, and you have the same signals recorded from a different position in space. As long as you know the microphone positions, its easy to determine the relative positions of the two instruments, aurally or mathematically. Yet when you add in the effects of the reverberant sound field you have a whole new set of signals of varying strengths and arrival times, and thus phase differences. As a listener, in place of the microphones, even minor head movements allow you to localize the instruments by sampling different angular presentations (i.e. the HRTF effect) and analyzing multiple wave fronts. This depth of information is simply not captured in a stereo recording. Sure it is. It's capture by only two mikes (ideally), but in the right circumstances, that's enough. How is it captured? I'm not referring to *soundstage* depth, clearly that only requires two mics, rather I'm talking about information density. A listener, with only minute head movements, samples a number of different wavefronts, providing an information density much greater than that achieved by any fixed recording setup, whether stereo, multichannel, or binaural. That is the information that is missing; that's the information that allows us to establish accurate positional data. I maintain that in a properly made recording, it's not missing. I believe the information to which I'm referring is missing from the recording. Where, in a stereo recording, is information from multiple wavefronts, both normal and off-angle, recorded? There is no doubt that there is sufficient information in a stereo recording to create a left/right soundstage, as well as depth localization, and at least an illusion of height, although I admit I don't have a firm geometric/visual conception of quite how that is achieved. But the ability to sample a virtually endless number of stereophonic (relative to listener reception) wavefronts, available to an audience member, does not translate to a recording made from any fixed perspective. If I'm missing something here, feel free to enlighten me. As I stated previously, I don't claim any special expertise in recording technologies. But many things in our hobby do not require such expertise to understand. Keith |
#23
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On Mon, 18 Jun 2012 03:39:56 -0700, KH wrote
(in article ): On 6/17/2012 6:34 PM, Audio Empire wrote: On Sun, 17 Jun 2012 12:59:06 -0700, KH wrote (in ): snip So add a second microphone, and you have the same signals recorded from a different position in space. As long as you know the microphone positions, its easy to determine the relative positions of the two instruments, aurally or mathematically. Yet when you add in the effects of the reverberant sound field you have a whole new set of signals of varying strengths and arrival times, and thus phase differences. As a listener, in place of the microphones, even minor head movements allow you to localize the instruments by sampling different angular presentations (i.e. the HRTF effect) and analyzing multiple wave fronts. This depth of information is simply not captured in a stereo recording. Sure it is. It's capture by only two mikes (ideally), but in the right circumstances, that's enough. How is it captured? I'm not referring to *soundstage* depth, clearly that only requires two mics, rather I'm talking about information density. A listener, with only minute head movements, samples a number of different wavefronts, providing an information density much greater than that achieved by any fixed recording setup, whether stereo, multichannel, or binaural. I think that the soundfield, by the time it reaches the audience, has coalesced into a single whole that is perceived in a certain way from each location within the audience. The human brain allows us to search within that soundfield and pick out certain sounds upon which to concentrate, but that's part of the human ear/intelligence interface that allows us to pick certain sounds out of a plethora of background. I.E. it's a survival skill that allows us to pick out the snap of a twig against a waterfall, or for a mother to distinguish her lost child crying in a crowd. It is not a result of the orchestra being comprised of many different soundfields which moving our heads allows us to intersect and sample, and which microphones miss because they are locked in a single location. That is the information that is missing; that's the information that allows us to establish accurate positional data. I maintain that in a properly made recording, it's not missing. I believe the information to which I'm referring is missing from the recording. Where, in a stereo recording, is information from multiple wavefronts, both normal and off-angle, recorded? It's not necessary as there aren't multiple wavefronts, or if their are, both our microphones and our ears intersect all of them arriving at that point in space. There is no doubt that there is sufficient information in a stereo recording to create a left/right soundstage, as well as depth localization, and at least an illusion of height, although I admit I don't havee a firm geometric/visual conception of quite how that is achieved. Subtle phase differences that give out ears the (relative) height of a sound source. They are captured by microphones too in a true stereo recording. But the ability to sample a virtually endless number of stereophonic (relative to listener reception) wavefronts, available to an audience member, does not translate to a recording made from any fixed perspective. If you accept the premise, then your conclusion is correct. However from my knowledge and experience, I find that your premise isn't correct. |
#24
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Posted to rec.audio.high-end
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On 6/18/2012 4:46 PM, Audio Empire wrote:
On Mon, 18 Jun 2012 03:39:56 -0700, KH wrote (in ): On 6/17/2012 6:34 PM, Audio Empire wrote: On Sun, 17 Jun 2012 12:59:06 -0700, KH wrote (in ): snip How is it captured? I'm not referring to *soundstage* depth, clearly that only requires two mics, rather I'm talking about information density. A listener, with only minute head movements, samples a number of different wavefronts, providing an information density much greater than that achieved by any fixed recording setup, whether stereo, multichannel, or binaural. I think that the soundfield, by the time it reaches the audience, has coalesced into a single whole that is perceived in a certain way from each location within the audience. I agree, relative to any specific head orientation. But not as the head is turned to sample different incident angle information. The human brain allows us to search within that soundfield and pick out certain sounds upon which to concentrate, but that's part of the human ear/intelligence interface that allows us to pick certain sounds out of a plethora of background. I.E. it's a survival skill that allows us to pick out the snap of a twig against a waterfall, or for a mother to distinguish her lost child crying in a crowd. It is not a result of the orchestra being comprised of many different soundfields which moving our heads allows us to intersect and sample, and which microphones miss because they are locked in a single location. I don't think that's quite accurate. You can think of it in simple geometric terms. If you look directly at the center of the soundfield - both ears equidistant from the center of the stage, you're 'sampling' one perspective of the soundfield. If you turn your head left 10 degrees, there is now a clear separation in the arrival time of any given sound ear to ear, a sound previously reaching each ear at the same time (from the center of the stage), simultaneously you will hear a higher ratio of reverberant to direct information in the left ear, and, possibly, a lower ratio in the right ear. A situation the brain has evolved to interpret into location clues. That is the information that is missing; that's the information that allows us to establish accurate positional data. I maintain that in a properly made recording, it's not missing. I believe the information to which I'm referring is missing from the recording. Where, in a stereo recording, is information from multiple wavefronts, both normal and off-angle, recorded? It's not necessary as there aren't multiple wavefronts, or if their are, both our microphones and our ears intersect all of them arriving at that point in space. Well, I believe that yes, there are multiple wavefronts in the sense that turning your head will provide a different perspective to each ear, and those differences in perspective allow the ear and brain to localize sounds in three dimensions. Obviously, the ability to discriminate different off-angle perspectives is subject to threshold values, and sensitivity and precision constraints, all of which will vary to a certain degree among individuals. Again, I'm not saying there's not enough information in the recording to create a very good reproduction. But, if we're talking about some theory that would create a playback method/environment/setup that would be a new paradigm of realism, and overcome all preferential effects, then close won't do. There is no doubt that there is sufficient information in a stereo recording to create a left/right soundstage, as well as depth localization, and at least an illusion of height, although I admit I don't havee a firm geometric/visual conception of quite how that is achieved. Subtle phase differences that give out ears the (relative) height of a sound source. They are captured by microphones too in a true stereo recording. That I get. From a visual geometry perspective, I don't have a mental image that accounts for height differences. Left/right, front/back, fairly clear. Height, not so much, unless frequency plays a role in height assessment. But the ability to sample a virtually endless number of stereophonic (relative to listener reception) wavefronts, available to an audience member, does not translate to a recording made from any fixed perspective. If you accept the premise, then your conclusion is correct. However from my knowledge and experience, I find that your premise isn't correct. Ignoring threshold effects, I don't see how it could not be correct. Not in the sense of different overall soundfields intertwined in the venue, but rather different stereophonic interpretations of the overall soundfield when evaluated from different incident angles. It's fairly obvious that when you look ahead, look at the right wall, then look at the left wall, the sound changes significantly. Keith |
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On Mon Jun 18 23:46:13 2012 Audio Empire wrote:
On Mon, 18 Jun 2012 03:39:56 -0700, KH wrote Subtle phase differences that give out ears the (relative) height of a sound source. They are captured by microphones too in a true stereo recording. But the ability to sample a virtually endless number of stereophonic (relative to listener reception) wavefronts, available to an audience member, does not translate to a recording made from any fixed perspective. If you accept the premise, then your conclusion is correct. However from my knowledge and experience, I find that your premise isn't correct. There are no "subtle phase differences" beyond about 700 Hz, at which point the wavelength becomes too small for the perception of any phase effects, and pure time difference takes over. Phase has some effect below that point, but that region is not a biggie in spacial perception. Gary Eickmeier |
#26
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On Mon, 18 Jun 2012 19:20:16 -0700, KH wrote
(in article ): On 6/18/2012 4:46 PM, Audio Empire wrote: On Mon, 18 Jun 2012 03:39:56 -0700, KH wrote (in ): On 6/17/2012 6:34 PM, Audio Empire wrote: On Sun, 17 Jun 2012 12:59:06 -0700, KH wrote (in ): snip How is it captured? I'm not referring to *soundstage* depth, clearly that only requires two mics, rather I'm talking about information density. A listener, with only minute head movements, samples a number of different wavefronts, providing an information density much greater than that achieved by any fixed recording setup, whether stereo, multichannel, or binaural. I think that the soundfield, by the time it reaches the audience, has coalesced into a single whole that is perceived in a certain way from each location within the audience. I agree, relative to any specific head orientation. But not as the head is turned to sample different incident angle information. I think that's the ear/brain at work and not anythning to do with the soundfield. The human brain allows us to search within that soundfield and pick out certain sounds upon which to concentrate, but that's part of the human ear/intelligence interface that allows us to pick certain sounds out of a plethora of background. I.E. it's a survival skill that allows us to pick out the snap of a twig against a waterfall, or for a mother to distinguish her lost child crying in a crowd. It is not a result of the orchestra being comprised of many different soundfields which moving our heads allows us to intersect and sample, and which microphones miss because they are locked in a single location. I don't think that's quite accurate. You can think of it in simple geometric terms. If you look directly at the center of the soundfield - both ears equidistant from the center of the stage, you're 'sampling' one perspective of the soundfield. If you turn your head left 10 degrees, there is now a clear separation in the arrival time of any given sound ear to ear, a sound previously reaching each ear at the same time (from the center of the stage), simultaneously you will hear a higher ratio of reverberant to direct information in the left ear, and, possibly, a lower ratio in the right ear. A situation the brain has evolved to interpret into location clues. My experiements with microphone placement tells me that this is NOT what's going on. That is the information that is missing; that's the information that allows us to establish accurate positional data. I maintain that in a properly made recording, it's not missing. I believe the information to which I'm referring is missing from the recording. Where, in a stereo recording, is information from multiple wavefronts, both normal and off-angle, recorded? It's not necessary as there aren't multiple wavefronts, or if their are, both our microphones and our ears intersect all of them arriving at that point in space. Well, I believe that yes, there are multiple wavefronts in the sense that turning your head will provide a different perspective to each ear, and those differences in perspective allow the ear and brain to localize sounds in three dimensions. Obviously, the ability to discriminate different off-angle perspectives is subject to threshold values, and sensitivity and precision constraints, all of which will vary to a certain degree among individuals. Again, I'm not saying there's not enough information in the recording to create a very good reproduction. But, if we're talking about some theory that would create a playback method/environment/setup that would be a new paradigm of realism, and overcome all preferential effects, then close won't do. There is no doubt that there is sufficient information in a stereo recording to create a left/right soundstage, as well as depth localization, and at least an illusion of height, although I admit I don't havee a firm geometric/visual conception of quite how that is achieved. Subtle phase differences that give out ears the (relative) height of a sound source. They are captured by microphones too in a true stereo recording. That I get. From a visual geometry perspective, I don't have a mental image that accounts for height differences. Left/right, front/back, fairly clear. Height, not so much, unless frequency plays a role in height assessment. But the ability to sample a virtually endless number of stereophonic (relative to listener reception) wavefronts, available to an audience member, does not translate to a recording made from any fixed perspective. If you accept the premise, then your conclusion is correct. However from my knowledge and experience, I find that your premise isn't correct. Ignoring threshold effects, I don't see how it could not be correct. Not in the sense of different overall soundfields intertwined in the venue, but rather different stereophonic interpretations of the overall soundfield when evaluated from different incident angles. It's fairly obvious that when you look ahead, look at the right wall, then look at the left wall, the sound changes significantly. Keith Different strokes for different folks, I guess. I have done countless experiments with microphones and the things that those experiments have taught me is that it's real easy to over think this question. There are a number of fundamentals and it takes a certain insight to be able to "see" like a microphone sees (talent, maybe?), but once you understand what microphone movements will result in an actual change in perspective and which ones won't, you begging to realize what you are dealing with in terms of the physics of stereo recording. |
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On Mon, 18 Jun 2012 20:21:01 -0700, Gary Eickmeier wrote
(in article ): On Mon Jun 18 23:46:13 2012 Audio Empire wrote: On Mon, 18 Jun 2012 03:39:56 -0700, KH wrote Subtle phase differences that give out ears the (relative) height of a sound source. They are captured by microphones too in a true stereo recording. But the ability to sample a virtually endless number of stereophonic (relative to listener reception) wavefronts, available to an audience member, does not translate to a recording made from any fixed perspective. If you accept the premise, then your conclusion is correct. However from my knowledge and experience, I find that your premise isn't correct. There are no "subtle phase differences" beyond about 700 Hz, at which point the wavelength becomes too small for the perception of any phase effects, and pure time difference takes over. Phase has some effect below that point, but that region is not a biggie in spacial perception. Gary Eickmeier You're going to have to provide some provenance for that statement. |
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Gary Eickmeier wrote:
On Mon Jun 18 23:46:13 2012 Audio Empire wrote: On Mon, 18 Jun 2012 03:39:56 -0700, KH wrote Subtle phase differences that give out ears the (relative) height of a sound source. They are captured by microphones too in a true stereo recording. But the ability to sample a virtually endless number of stereophonic (relative to listener reception) wavefronts, available to an audience member, does not translate to a recording made from any fixed perspective. If you accept the premise, then your conclusion is correct. However from my knowledge and experience, I find that your premise isn't correct. There are no "subtle phase differences" beyond about 700 Hz, at which point the wavelength becomes too small for the perception of any phase effects, and pure time difference takes over. This does not agree with things I have read. Please provide source for that information... rgds \SK -- "Never underestimate the power of human stupidity" -- L. Lang -- http://www.tajga.org -- (some photos from my travels) |
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"Sebastian Kaliszewski" wrote in message
... Gary Eickmeier wrote: There are no "subtle phase differences" beyond about 700 Hz, at which point the wavelength becomes too small for the perception of any phase effects, and pure time difference takes over. This does not agree with things I have read. Please provide source for that information... Sorry, thought this was well known. The best reference I found is in the AES Anthology of Stereophonic Techniques, James Moir, "Stereophonic Reproduction," Audio Engineering, 1952 October, pp. 26 - 28. I quote in part: "These differences justify further discussion. The reason for the difference in time of arrival at the two ears is evident and requires no further exlanation, but the question immediately arises as to which part of the sound-wave cycle is accepted by the ear as determining the time of arrival at that ear. On an impulsive sound having a steep wave front it may be assumed that the arrival of the wave front is recognized, but on a repetitive waveform there is difficulty in understanding just how the ear recognizes the difference between successive cycles with identical waveform. A high frequency wave passing from right to left will have several cycles pass the right ear before the first cycle reaches the left ear, and the right ear may not know just how many cycles have passed at the instant the first cycle reaches the left ear. This rather suggests that there may be difficulty in fixing the position of a high frequency source having a frequency such that more than half to one cycle of the wave can be accomodated in the space between the ears. Taking the velocity of sound as 33,000 cm/sec and the ear spacing as 21 cm, it might be expected that frequencies above 800 cps (half wave = 21 cm) might present difficulties in location and it is worth noting that this is found to be the case in practice." In other words, at frequencies above 800 Hz a time difference can result in a phase difference at low frequencies, but at higher freqs phase makes no sense. In other well-known literature such as Blauert, the statement about level vs time of arrival differences is that the signal will be slammed completely right or left with level difference of 30 dB or a time difference of 630 microseconds to 1 ms. I note also that with AE's favorite recording technique of coincindent miking, or Blumlein stereo, there is NO time of arrival or phase difference between channels. Gary Eickmeier |
#30
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On Wed, 20 Jun 2012 16:55:04 -0700, Gary Eickmeier wrote
(in article ): "Sebastian Kaliszewski" wrote in message ... Gary Eickmeier wrote: There are no "subtle phase differences" beyond about 700 Hz, at which point the wavelength becomes too small for the perception of any phase effects, and pure time difference takes over. This does not agree with things I have read. Please provide source for that information... Sorry, thought this was well known. The best reference I found is in the AES Anthology of Stereophonic Techniques, James Moir, "Stereophonic Reproduction," Audio Engineering, 1952 October, pp. 26 - 28. I quote in part: "These differences justify further discussion. The reason for the difference in time of arrival at the two ears is evident and requires no further exlanation, but the question immediately arises as to which part of the sound-wave cycle is accepted by the ear as determining the time of arrival at that ear. On an impulsive sound having a steep wave front it may be assumed that the arrival of the wave front is recognized, but on a repetitive waveform there is difficulty in understanding just how the ear recognizes the difference between successive cycles with identical waveform. A high frequency wave passing from right to left will have several cycles pass the right ear before the first cycle reaches the left ear, and the right ear may not know just how many cycles have passed at the instant the first cycle reaches the left ear. This rather suggests that there may be difficulty in fixing the position of a high frequency source having a frequency such that more than half to one cycle of the wave can be accomodated in the space between the ears. Taking the velocity of sound as 33,000 cm/sec and the ear spacing as 21 cm, it might be expected that frequencies above 800 cps (half wave = 21 cm) might present difficulties in location and it is worth noting that this is found to be the case in practice." In other words, at frequencies above 800 Hz a time difference can result in a phase difference at low frequencies, but at higher freqs phase makes no sense. In other well-known literature such as Blauert, the statement about level vs time of arrival differences is that the signal will be slammed completely right or left with level difference of 30 dB or a time difference of 630 microseconds to 1 ms. This MIGHT be true if we're dealing with sine waves, but neither a musical instrument nor a musical ensemble produces sine waves. Also, the frequecy doesn't matter unless we are talking about two or more sine wave signals of the same frequency, but music is a complex waveform and the ear/brain's interaction with that waveform is not well understood at best. I note also that with AE's favorite recording technique of coincindent miking, or Blumlein stereo, there is NO time of arrival or phase difference between channels. That's ridiculous. phase differences start at the SOURCE of the wavefront, not at the destination (in this case, the microphones, where they already exist). No two sound sources are ever completely in phase at the same time. In fact one instrument will produce a complex wave-form that has many different phase relationships occurring at once within it's own sound. |
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On Tue Jun 19 02:20:16 2012 KH wrote:
On 6/18/2012 4:46 PM, Audio Empire wrote: On Mon, 18 Jun 2012 03:39:56 -0700, KH wrote (in But the ability to sample a virtually endless number of stereophonic (relative to listener reception) wavefronts, available to an audience member, does not translate to a recording made from any fixed perspective. If you accept the premise, then your conclusion is correct. However from my knowledge and experience, I find that your premise isn't correct. Ignoring threshold effects, I don't see how it could not be correct. Not in the sense of different overall soundfields intertwined in the venue, but rather different stereophonic interpretations of the overall soundfield when evaluated from different incident angles. It's fairly obvious that when you look ahead, look at the right wall, then look at the left wall, the sound changes significantly. I have told you that it doesn't work that way. You are setting up a new sound field within your listening room. If it is done right, then you can turn your head all you want within that new field, with similar results to those you get live. I routinely "see" instruments in my listening room, and can turn my head in subtle movements toward those sounds just as in the live venue. It is not a head related system. The resultant sound need not be from a fixed perspective. Example, the center channel with dialog for movies, or a solo singer for stereo. You can go anywhere in the room and it will stay where it belongs, and be perceived where it belongs, and you can turn toward it as you please, just as you can toward a left or right channel sound, or anything in between. Gary Eickmeier |
#32
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"Audio Empire" wrote in message
... On Wed, 20 Jun 2012 16:55:04 -0700, Gary Eickmeier wrote (in article ): In other words, at frequencies above 800 Hz a time difference can result in a phase difference at low frequencies, but at higher freqs phase makes no sense. In other well-known literature such as Blauert, the statement about level vs time of arrival differences is that the signal will be slammed completely right or left with level difference of 30 dB or a time difference of 630 microseconds to 1 ms. This MIGHT be true if we're dealing with sine waves, but neither a musical instrument nor a musical ensemble produces sine waves. Also, the frequecy doesn't matter unless we are talking about two or more sine wave signals of the same frequency, but music is a complex waveform and the ear/brain's interaction with that waveform is not well understood at best. Stan Lip****z, in his famous article "Stereo Microphone Techniques - Are the Purists Wrong?" (JAES 1986 September) puts it like this: "When listening live, the signals at the two eardrums differ in time of arrival, level, and spectral content, and these differences depend on the source position. The time of arrival difference is due to the physical spacing of our ears and cannot exceed about 630 microseconds in real life. This corresponds to a path length difference of about 210 mm, and this in turn represents a half wavelength at a frequency of around 800 Hz. It thus follows that for frequencies below about 800 Hz there is an unambiguous phase relationship between the two ear signals and the source direction, the ear nearer the source having the leading phase. This is what I shall call the low frequency regime. This phase difference is frequency dependent; in fact it varies linearly with frequency since it represents a pure time delay. At frequencies above about 800 Hz the interaural phase shift can exceed 180 degrees, and so the ability (on periodic steady state signals) to discern which ear's signal is leading and which is lagging is lost. So, clearly, interaural phase relationships would appear to be useful cues only at low freuencies." I note also that with AE's favorite recording technique of coincindent miking, or Blumlein stereo, there is NO time of arrival or phase difference between channels. That's ridiculous. phase differences start at the SOURCE of the wavefront, not at the destination (in this case, the microphones, where they already exist). No two sound sources are ever completely in phase at the same time. In fact one instrument will produce a complex wave-form that has many different phase relationships occurring at once within it's own sound. Now you're being silly. Phase differences between what and what? Two sound sources in phase? If they are two completely different sources, there is no such thing as phase relationships between them. Phase relationships within the sound of a single instrument? What in blazes are you talking about? Gary Eickmeier |
#33
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On 6/21/2012 4:07 AM, Gary Eickmeier wrote:
On Tue Jun 19 02:20:16 2012 KH wrote: On 6/18/2012 4:46 PM, Audio Empire wrote: On Mon, 18 Jun 2012 03:39:56 -0700, KH wrote (in But the ability to sample a virtually endless number of stereophonic (relative to listener reception) wavefronts, available to an audience member, does not translate to a recording made from any fixed perspective. If you accept the premise, then your conclusion is correct. However from my knowledge and experience, I find that your premise isn't correct. Ignoring threshold effects, I don't see how it could not be correct. Not in the sense of different overall soundfields intertwined in the venue, but rather different stereophonic interpretations of the overall soundfield when evaluated from different incident angles. It's fairly obvious that when you look ahead, look at the right wall, then look at the left wall, the sound changes significantly. I have told you that it doesn't work that way. Yes, and A) you can "tell" me anything you want, but assertions lacking data are not compelling in the least, and B) you continually misread, misunderstand, and/or misconstrue what I write. As with: You are setting up a new sound field within your listening room. A non-cogent statement interjected into a discussion about *venue* and *recording environment*. Nothing to do with the reproduction except in the context of what information is not captured on the recording. Keith |
#34
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On Thu, 21 Jun 2012 04:07:18 -0700, Gary Eickmeier wrote
(in article ): "Audio Empire" wrote in message ... On Wed, 20 Jun 2012 16:55:04 -0700, Gary Eickmeier wrote (in article ): In other words, at frequencies above 800 Hz a time difference can result in a phase difference at low frequencies, but at higher freqs phase makes no sense. In other well-known literature such as Blauert, the statement about level vs time of arrival differences is that the signal will be slammed completely right or left with level difference of 30 dB or a time difference of 630 microseconds to 1 ms. This MIGHT be true if we're dealing with sine waves, but neither a musical instrument nor a musical ensemble produces sine waves. Also, the frequecy doesn't matter unless we are talking about two or more sine wave signals of the same frequency, but music is a complex waveform and the ear/brain's interaction with that waveform is not well understood at best. Stan Lip****z, in his famous article "Stereo Microphone Techniques - Are the Purists Wrong?" (JAES 1986 September) puts it like this: "When listening live, the signals at the two eardrums differ in time of arrival, level, and spectral content, and these differences depend on the source position. The time of arrival difference is due to the physical spacing of our ears and cannot exceed about 630 microseconds in real life. This corresponds to a path length difference of about 210 mm, and this in turn represents a half wavelength at a frequency of around 800 Hz. It thus follows that for frequencies below about 800 Hz there is an unambiguous phase relationship between the two ear signals and the source direction, the ear nearer the source having the leading phase. This is what I shall call the low frequency regime. This phase difference is frequency dependent; in fact it varies linearly with frequency since it represents a pure time delay. At frequencies above about 800 Hz the interaural phase shift can exceed 180 degrees, and so the ability (on periodic steady state signals) to discern which ear's signal is leading and which is lagging is lost. So, clearly, interaural phase relationships would appear to be useful cues only at low freuencies." I note also that with AE's favorite recording technique of coincindent miking, or Blumlein stereo, there is NO time of arrival or phase difference between channels. That's ridiculous. phase differences start at the SOURCE of the wavefront, not at the destination (in this case, the microphones, where they already exist). No two sound sources are ever completely in phase at the same time. In fact one instrument will produce a complex wave-form that has many different phase relationships occurring at once within it's own sound. Now you're being silly. Phase differences between what and what? Two sound sources in phase? If they are two completely different sources, there is no such thing as phase relationships between them. Phase relationships within the sound of a single instrument? What in blazes are you talking about? This isn't worth discussing. If you don't understand sound and how it works well enough to grasp the concept of the phase difference between fundamental and harmonics, or between one instrument and another playing together, then there is no use me trying to explain it. |
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