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#41
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"Bob Cain" wrote in message
Bob Cain wrote: Arny Krueger wrote: Sorry Bob, but I'm not buying. How about this, then: 1) It is the bulk velocity, the flow of air, at the rest position that propagates out as the velocity wave. Frankly, over my head. 2) The bulk velocity at the rest position is the same as the surface velocity of the piston. Frankly, over my head. And, finally: 3) In the frame of reference of the rest position of the piston, no Doppler shift can be observed. That seems wrong, because the following is right: In the frame of reference of the piston, no Doppler shift can be observed. That's the listener riding the same train as the whistle. |
#42
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"Arny Krueger" wrote in message news "Bob Cain" wrote in message Bob Cain wrote: Arny Krueger wrote: Sorry Bob, but I'm not buying. How about this, then: 1) It is the bulk velocity, the flow of air, at the rest position that propagates out as the velocity wave. Frankly, over my head. 2) The bulk velocity at the rest position is the same as the surface velocity of the piston. Frankly, over my head. And, finally: 3) In the frame of reference of the rest position of the piston, no Doppler shift can be observed. That seems wrong, because the following is right: In the frame of reference of the piston, no Doppler shift can be observed. That's the listener riding the same train as the whistle. It seems to me that the train/whistle anology is not a valid one for this purpose, because the train's motion and the whistle's sound are not being reproduced by the same source, as happens in a loudspeaker producing a complex waveform. If you make a recording of the train approaching and receeding from your listening position and play it back, you will hear exactly the same Doppler shift you heard when the train went by, and this can be confirmed by measurement. Conversely, if you make a recording of the whistle from the train and play it back on a speaker moving down the tracks at the same velocity as the train, you will hear the same doppler shift you heard from the passing train, even though there is no shift in the actual recording. The above logic actually has little to do with Doppler distortion in a speaker, but the fact remains that the train/whistle in not a valid anology! Making the assumption that a speaker produces Doppler shift because a whistle on a moving train does is a rationalization not based on the actual physical facts. Even moving the whistle back and forth in approximation of a moving speaker cone is not a valid anology, because the whistle's back and forth motion is not generated by the sound coming from the whistle, as it would be in a speaker reproducing a complex waveform. You're actually dealing with two separate sources producing separate waveforms. Mounting the whistle on the speaker cone still won't be a valid anology because the waveforms are not being reproduced by the same mechanism, two separate sources again. The only valid anology for what happens with a speaker reproducing a complex waveform would be some other single entity that is capable of reproducing the same complex waveform. Any suggestions? |
#43
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"Porky" "Arny Krueger" That's the listener riding the same train as the whistle. It seems to me that the train/whistle anology is not a valid one for this purpose, because the train's motion and the whistle's sound are not being reproduced by the same source, as happens in a loudspeaker producing a complex waveform. ** How so ? The whiste is mounted on the train. If you make a recording of the train approaching and receeding from your listening position and play it back, you will hear exactly the same Doppler shift you heard when the train went by, and this can be confirmed by measurement. Conversely, if you make a recording of the whistle from the train and play it back on a speaker moving down the tracks at the same velocity as the train, you will hear the same doppler shift you heard from the passing train, even though there is no shift in the actual recording. ** No kidding. The above logic actually has little to do with Doppler distortion in a speaker, but the fact remains that the train/whistle in not a valid anology! ** I saw no relevant facts go by - must have just whizzed past on an express train ....... Making the assumption that a speaker produces Doppler shift because a whistle on a moving train does is a rationalization not based on the actual physical facts. ** You rationalisations are far more extensive and non logical. Even moving the whistle back and forth in approximation of a moving speaker cone is not a valid anology, because the whistle's back and forth motion is not generated by the sound coming from the whistle, as it would be in a speaker reproducing a complex waveform. ** Huh ? Since when is a cone's motion *produced* by sound ??? You're actually dealing with two separate sources producing separate waveforms. Mounting the whistle on the speaker cone still won't be a valid anology because the waveforms are not being reproduced by the same mechanism, two separate sources again. The only valid anology for what happens with a speaker reproducing a complex waveform would be some other single entity that is capable of reproducing the same complex waveform. Any suggestions? ** Lay off the weed. ............ Phil |
#44
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"Phil Allison" wrote in message ... "Porky" "Arny Krueger" That's the listener riding the same train as the whistle. It seems to me that the train/whistle anology is not a valid one for this purpose, because the train's motion and the whistle's sound are not being reproduced by the same source, as happens in a loudspeaker producing a complex waveform. ** How so ? The whiste is mounted on the train. If you make a recording of the train approaching and receeding from your listening position and play it back, you will hear exactly the same Doppler shift you heard when the train went by, and this can be confirmed by measurement. Conversely, if you make a recording of the whistle from the train and play it back on a speaker moving down the tracks at the same velocity as the train, you will hear the same doppler shift you heard from the passing train, even though there is no shift in the actual recording. ** No kidding. The above logic actually has little to do with Doppler distortion in a speaker, but the fact remains that the train/whistle in not a valid anology! ** I saw no relevant facts go by - must have just whizzed past on an express train ....... Making the assumption that a speaker produces Doppler shift because a whistle on a moving train does is a rationalization not based on the actual physical facts. ** You rationalisations are far more extensive and non logical. Even moving the whistle back and forth in approximation of a moving speaker cone is not a valid anology, because the whistle's back and forth motion is not generated by the sound coming from the whistle, as it would be in a speaker reproducing a complex waveform. ** Huh ? Since when is a cone's motion *produced* by sound ??? You're actually dealing with two separate sources producing separate waveforms. Mounting the whistle on the speaker cone still won't be a valid anology because the waveforms are not being reproduced by the same mechanism, two separate sources again. The only valid anology for what happens with a speaker reproducing a complex waveform would be some other single entity that is capable of reproducing the same complex waveform. Any suggestions? ** Lay off the weed. The sound produced by the speaker happens because the speaker is driven by a single complex waveform, thus there is a single source for the sound. The sound that comes from a train whistle is generated by the whistle, and the motion imparted to the whistle comes from the train's motion, two separate sources. If you move the whistle back and forth in a manner approximating that of a speaker cone, you still have two sources, the whistle's sound and the mechanical vibration of the whistle, if you mount the whistle on the speaker cone, you have two sources, that driving the cone and that coming from the whistle. None of those approximates in any way, or is a valid anology for a loudspeaker producing a complex waveform that comes from only one source, the complex electrical waveform driving the speaker motor. All the other anologies have two sources, one for the low frequency motion and one for the high frequency sound, NOT a valid anology for what happens when a speaker reproduced a complex waveform. If you don't get that, then perhaps it is you who should "lay off the weed". You aren't going to get it until you can differentiate that which comes from two or more separate simple driving sources and that which comes from a single complex driving source BTW, I never said anything about a cone's motion being prodiuced by sound. I said "a speaker reproducing a complex waveform". |
#45
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"Porky" The sound produced by the speaker happens because the speaker is driven by a single complex waveform, thus there is a single source for the sound. The sound that comes from a train whistle is generated by the whistle, and the motion imparted to the whistle comes from the train's motion, two separate sources. ** WRONG !!! There is only one source of sound in both cases. Case 1 = the cone. Case 2 = the whistle. If you move the whistle back and forth in a manner approximating that of a speaker cone, you still have two sources, the whistle's sound and the mechanical vibration of the whistle, if you mount the whistle on the speaker cone, you have two sources, that driving the cone and that coming from the whistle. ** I told you to lay off that damn weed !! None of those approximates in any way, or is a valid anology for a loudspeaker producing a complex waveform that comes from only one source, the complex electrical waveform driving the speaker motor. ** The SOURCE source of any sound is the vibrating object or air column. All the other anologies have two sources, one for the low frequency motion and one for the high frequency sound, ** Simply not relevant. NOT a valid anology for what happens when a speaker reproduced a complex waveform. If you don't get that, then perhaps it is you who should "lay off the weed". ** There is nothing rational anywhere in your posts to get. You aren't going to get it until you can differentiate that which comes from two or more separate simple driving sources and that which comes from a single complex driving source ** Totally false distinction. It exists only in the words. BTW, I never said anything about a cone's motion being prodiuced by sound. I said "a speaker reproducing a complex waveform". ** Quote: " Even moving the whistle back and forth in approximation of a moving speaker cone is not a valid anology, because the whistle's back and forth motion is not generated by the sound coming from the whistle, as it would be in a speaker reproducing a complex waveform. " ** Yes you did, then deceitfully snipped it. Bet the weed made you do that...... ............ Phil |
#46
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"Porky" wrote in message
"Arny Krueger" wrote in message news "Bob Cain" wrote in message Bob Cain wrote: Arny Krueger wrote: Sorry Bob, but I'm not buying. How about this, then: 1) It is the bulk velocity, the flow of air, at the rest position that propagates out as the velocity wave. Frankly, over my head. 2) The bulk velocity at the rest position is the same as the surface velocity of the piston. Frankly, over my head. And, finally: 3) In the frame of reference of the rest position of the piston, no Doppler shift can be observed. That seems wrong, because the following is right: In the frame of reference of the piston, no Doppler shift can be observed. That's the listener riding the same train as the whistle. It seems to me that the train/whistle anology is not a valid one for this purpose, because the train's motion and the whistle's sound are not being reproduced by the same source, as happens in a loudspeaker producing a complex waveform. It's just a matter of scale. The world is the equivalent of the chassis of the speaker. The effective diaphragm of the whistel is the woofer cone. If you make a recording of the train approaching and receeding from your listening position and play it back, you will hear exactly the same Doppler shift you heard when the train went by, and this can be confirmed by measurement. And, if the train travels in a really large sine wave, it's a lot like a speaker. Conversely, if you make a recording of the whistle from the train and play it back on a speaker moving down the tracks at the same velocity as the train, you will hear the same doppler shift you heard from the passing train, even though there is no shift in the actual recording. Agreed.. The above logic actually has little to do with Doppler distortion in a speaker, but the fact remains that the train/whistle in not a valid anology! Have it your way, if that's what you want. I'm not buying that there is a substantial difference. Making the assumption that a speaker produces Doppler shift because a whistle on a moving train does is a rationalization not based on the actual physical facts. False. Even moving the whistle back and forth in approximation of a moving speaker cone is not a valid anology, because the whistle's back and forth motion is not generated by the sound coming from the whistle, as it would be in a speaker reproducing a complex waveform. Let's presume that the whistle is actually a mechanical horn with a diaphragm which of course undergoes the identical same Doppler shift as an air horn or steam whistle. The diaphragm of this mechanical train horn follows a similar path, different only in scale, from a woofer cone. You're actually dealing with two separate sources producing separate waveforms. Doesn't matter because the diaphragm that actually makes the sound follows a similar path. Mounting the whistle on the speaker cone still won't be a valid anology because the waveforms are not being reproduced by the same mechanism, two separate sources again. This turns out to be an irrelevant distinction. What matters is the path of the diaphragm, or its moral equivalent. The only valid anology for what happens with a speaker reproducing a complex waveform would be some other single entity that is capable of reproducing the same complex waveform. Any suggestions? A train, car or a boat. |
#47
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The sound produced by the speaker happens because the speaker is driven
None of those approximates in any way, or is a valid anology for a loudspeaker producing a complex waveform that comes from only one source, the complex electrical waveform driving the speaker motor. All the other anologies have two sources, one for the low frequency motion and one for the high frequency sound, NOT a valid anology for what happens when a speaker reproduced a complex waveform. What if we take this to the extremes with a thought experiment: Picture the largest loudspeaker in the universe sitting outside somewhere. It's so big that it has a maximal excursion of several feet. Now picture a very low bass signal played on that speaker at almost maximal volume. The speaker cone is vibrating in-out-in-out-in-out. Now add to that signal a small, high pitched, low amplitude waveform. The two waveforms are added together so that it seems like the higher pitched wave is "riding on top of" the bass wave. As far as our super-excursion speaker is concerned, the location that's generating the high pitched sound is moving forward and backward several feet. If you still don't believe that this scenario validates the train-whistle analogy, why not make the bass waveform move at the speed of, oh say a train, and have the high pitched signal on top of it be, oh say the sound of a whistle. The scenario described in this thought experiment would *certainly* produce doppler shift in the higher signals. If you made the bass carrier sound low enough frequency and loud enough, you would even be able to hear the weeeooohhweeeoooh modulation of the higher frequency as the source of that sound (the surface of the speaker cone) is moving towards and away from you. It follows reasonably that this also happens with regular speakers, but to a lesser extent. The question of whether it's a relevant, measurable, or hearable distortion is a separate issue from whether it physically exists. Forgive me if this has already been discussed to this point, I didn't have time to read the entire thread. Ken |
#48
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"PenguiN" What if we take this to the extremes with a thought experiment: Picture the largest loudspeaker in the universe sitting outside somewhere. It's so big that it has a maximal excursion of several feet. Now picture a very low bass signal played on that speaker at almost maximal volume. The speaker cone is vibrating in-out-in-out-in-out. Now add to that signal a small, high pitched, low amplitude waveform. The two waveforms are added together so that it seems like the higher pitched wave is "riding on top of" the bass wave. As far as our super-excursion speaker is concerned, the location that's generating the high pitched sound is moving forward and backward several feet. If you still don't believe that this scenario validates the train-whistle analogy, why not make the bass waveform move at the speed of, oh say a train, and have the high pitched signal on top of it be, oh say the sound of a whistle. The scenario described in this thought experiment would *certainly* produce doppler shift in the higher signals. If you made the bass carrier sound low enough frequency and loud enough, you would even be able to hear the weeeooohhweeeoooh modulation of the higher frequency as the source of that sound (the surface of the speaker cone) is moving towards and away from you. It follows reasonably that this also happens with regular speakers, but to a lesser extent. The question of whether it's a relevant, measurable, or hearable distortion is a separate issue from whether it physically exists. Forgive me if this has already been discussed to this point, I didn't have time to read the entire thread. Ken ** I reckon Ken must be an ambulatoy gum chewer. ........... Phil |
#49
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ruffrecords writes:
PenguiN wrote: The sound produced by the speaker happens because the speaker is driven None of those approximates in any way, or is a valid anology for a loudspeaker producing a complex waveform that comes from only one source, the complex electrical waveform driving the speaker motor. All the other anologies have two sources, one for the low frequency motion and one for the high frequency sound, NOT a valid anology for what happens when a speaker reproduced a complex waveform. What if we take this to the extremes with a thought experiment: Picture the largest loudspeaker in the universe sitting outside somewhere. It's so big that it has a maximal excursion of several feet. Now picture a very low bass signal played on that speaker at almost maximal volume. The speaker cone is vibrating in-out-in-out-in-out. Now add to that signal a small, high pitched, low amplitude waveform. The two waveforms are added together so that it seems like the higher pitched wave is "riding on top of" the bass wave. What gets added are the instantaneous pressures. The air pressure produced is exactly the same as two separate speakers at the two frequencies. There is no such thing as doppler distortion. Consider this gedanken: Place a 4-inch speaker on the cone of a 14-foot speaker. Now, the two speakers are fed different signals. Is there Doppler? Yes. Use the one 14-foot speaker for both frequencies. Is there Doppler? Left as an exercise for the student. Granted, there will be differences, but the lack of doppler will not be one of them. One of them will be the dispersion characterstics of the high-frequency signal. The difference between receiving two such summed signals electrically versus acoustically is that one has the physical phenomenom of the propagation of sound through the air in one case and not in the other. Similarly, an electronic receiver may have other types of non-linear distortion (e.g., clipping) depending on the circuit and parameters that an acoustic receiver would not have. The two do not necessarily have to agree with one another - there are different physical processes that occur in each. Get out a physics book and read about Doppler. The explanation of how the observed wavelength changes when there is a relative velocity between the source and observer should make you a believer that this is precisely the scene in a speaker reproducing two frequencies. -- Randy Yates Sony Ericsson Mobile Communications Research Triangle Park, NC, USA , 919-472-1124 |
#50
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"ruffrecords" wrote in message
PenguiN wrote: As far as our super-excursion speaker is concerned, the location that's generating the high pitched sound is moving forward and backward several feet. No it isn't. This is the flaw in all the doppler distortion arguments. If all the explanations for Doppler distortion are wrong, where does all of the FM we measure come from? Why does it correlate well with the *incorrect* theoretical predictions? |
#51
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PenguiN wrote:
The sound produced by the speaker happens because the speaker is driven None of those approximates in any way, or is a valid anology for a loudspeaker producing a complex waveform that comes from only one source, the complex electrical waveform driving the speaker motor. All the other anologies have two sources, one for the low frequency motion and one for the high frequency sound, NOT a valid anology for what happens when a speaker reproduced a complex waveform. What if we take this to the extremes with a thought experiment: Picture the largest loudspeaker in the universe sitting outside somewhere. It's so big that it has a maximal excursion of several feet. Now picture a very low bass signal played on that speaker at almost maximal volume. The speaker cone is vibrating in-out-in-out-in-out. Now add to that signal a small, high pitched, low amplitude waveform. The two waveforms are added together so that it seems like the higher pitched wave is "riding on top of" the bass wave. What gets added are the instantaneous pressures. The air pressure produced is exactly the same as two separate speakers at the two frequencies. There is no such thing as doppler distortion. Ian As far as our super-excursion speaker is concerned, the location that's generating the high pitched sound is moving forward and backward several feet. No it isn't. This is the flaw in all the doppler distortion arguments. Ian |
#53
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On Sun, 15 Aug 2004 22:56:47 -0700, Bob Cain
wrote: Porky wrote: At that velocity, it simply doesn't have time to dopple!:-) That's cute. Wrong, but nonetheless cute. :-) It WILL cause a phase shift, and I have no doubt you can set this up and see a practical demonstration of this on an oscilloscope, and phase shift, no matter how slow, IS equivalent to a frequency change. It dopples, just as surely at the Earth moves. Bob ----- http://mindspring.com/~benbradley |
#54
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Arny Krueger wrote: "Bob Cain" wrote in message Porky wrote: True, but who's going to hear doppler shift at that level, even if it does exist?:-) To me it doesn't matter whether we can hear it or not. As of now there is no predictive theory that yields quantitative results we could test with experiment anyway. I want to know whether or not it is a real phenomenon at all. How are you doing with the 60KB or so of AES paper references that I posted in RAP? Not well without access to the papers. If you can point me to at least one of them that solves the problem analytically to yield a general mathematical description I'll purhase it. Bob -- "Things should be described as simply as possible, but no simpler." A. Einstein |
#55
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Arny Krueger wrote: "Bob Cain" wrote in message Bob Cain wrote: Arny Krueger wrote: Sorry Bob, but I'm not buying. How about this, then: 1) It is the bulk velocity, the flow of air, at the rest position that propagates out as the velocity wave. Frankly, over my head. That's hard to believe. What part of it evades you? 2) The bulk velocity at the rest position is the same as the surface velocity of the piston. Frankly, over my head. Same. And, finally: 3) In the frame of reference of the rest position of the piston, no Doppler shift can be observed. That seems wrong, because the following is right: In the frame of reference of the piston, no Doppler shift can be observed. If you are in the frame of reference of the piston, you're going to get shanken _all_ to hell. :-) Bob -- "Things should be described as simply as possible, but no simpler." A. Einstein |
#56
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"Bob Cain" wrote in message
Arny Krueger wrote: "Bob Cain" wrote in message 3) In the frame of reference of the rest position of the piston, no Doppler shift can be observed. That seems wrong, because the following is right: In the frame of reference of the piston, no Doppler shift can be observed. If you are in the frame of reference of the piston, you're going to get shanken _all_ to hell. :-) Agreed. Hey, you think getting zero Doppler is always painless? ;-) |
#57
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Randy Yates wrote:
ruffrecords writes: PenguiN wrote: The sound produced by the speaker happens because the speaker is driven None of those approximates in any way, or is a valid anology for a loudspeaker producing a complex waveform that comes from only one source, the complex electrical waveform driving the speaker motor. All the other anologies have two sources, one for the low frequency motion and one for the high frequency sound, NOT a valid anology for what happens when a speaker reproduced a complex waveform. What if we take this to the extremes with a thought experiment: Picture the largest loudspeaker in the universe sitting outside somewhere. It's so big that it has a maximal excursion of several feet. Now picture a very low bass signal played on that speaker at almost maximal volume. The speaker cone is vibrating in-out-in-out-in-out. Now add to that signal a small, high pitched, low amplitude waveform. The two waveforms are added together so that it seems like the higher pitched wave is "riding on top of" the bass wave. What gets added are the instantaneous pressures. The air pressure produced is exactly the same as two separate speakers at the two frequencies. There is no such thing as doppler distortion. Consider this gedanken: Place a 4-inch speaker on the cone of a 14-foot speaker. Now, the two speakers are fed different signals. Consider this. place a 14ft speaker next to a 4inch speaker and feed them different signals. Is there Doppler? No The difference between receiving two such summed signals electrically versus acoustically is that one has the physical phenomenom of the propagation of sound through the air in one case and not in the other. I did not mention electrical adding of the signals. Get out a physics book and read about Doppler. The explanation of how the observed wavelength changes when there is a relative velocity between the source and observer should make you a believer that this is precisely the scene in a speaker reproducing two frequencies. get an electrical test book and read about linear superpostion. Ian |
#58
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ruffrecords writes:
Randy Yates wrote: ruffrecords writes: PenguiN wrote: The sound produced by the speaker happens because the speaker is driven None of those approximates in any way, or is a valid anology for a loudspeaker producing a complex waveform that comes from only one source, the complex electrical waveform driving the speaker motor. All the other anologies have two sources, one for the low frequency motion and one for the high frequency sound, NOT a valid anology for what happens when a speaker reproduced a complex waveform. What if we take this to the extremes with a thought experiment: Picture the largest loudspeaker in the universe sitting outside somewhere. It's so big that it has a maximal excursion of several feet. Now picture a very low bass signal played on that speaker at almost maximal volume. The speaker cone is vibrating in-out-in-out-in-out. Now add to that signal a small, high pitched, low amplitude waveform. The two waveforms are added together so that it seems like the higher pitched wave is "riding on top of" the bass wave. What gets added are the instantaneous pressures. The air pressure produced is exactly the same as two separate speakers at the two frequencies. There is no such thing as doppler distortion. Consider this gedanken: Place a 4-inch speaker on the cone of a 14-foot speaker. Now, the two speakers are fed different signals. Consider this. place a 14ft speaker next to a 4inch speaker and feed them different signals. Is there Doppler? No Hey man, stay stupid - see if I give a ****. The difference between receiving two such summed signals electrically versus acoustically is that one has the physical phenomenom of the propagation of sound through the air in one case and not in the other. I did not mention electrical adding of the signals. Get out a physics book and read about Doppler. The explanation of how the observed wavelength changes when there is a relative velocity between the source and observer should make you a believer that this is precisely the scene in a speaker reproducing two frequencies. get an electrical test book and read about linear superpostion. You mean a text on linear system theory and/or basic circuit analysis? Like Oppenheim and Willsky's "Signals and Systems"? Or Sedra and Smith's "Microelectronic Circuits"? Or how about the old standard, Boylestad's "Circuit Analysis"? I've read those books over the course of 20 years and two degrees in electrical engineering. I've also read about the migratory behavior of sperm whales, but neither one have anything to do with the Doppler effect in speakers. So forget this argument and go buy another eighth of sensamilla at your local pot store. -- Randy Yates Sony Ericsson Mobile Communications Research Triangle Park, NC, USA , 919-472-1124 |
#59
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Arny Krueger wrote:
"ruffrecords" wrote in message PenguiN wrote: As far as our super-excursion speaker is concerned, the location that's generating the high pitched sound is moving forward and backward several feet. No it isn't. This is the flaw in all the doppler distortion arguments. If all the explanations for Doppler distortion are wrong, where does all of the FM we measure come from? Why does it correlate well with the *incorrect* theoretical predictions? To produce FM there needs to be a non-linearity. If you detect FM there is a good chance a non-linearity exists. But it is not due to the doppler effect. Ian |
#60
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ruffrecords wrote: To produce FM there needs to be a non-linearity. If you detect FM there is a good chance a non-linearity exists. But it is not due to the doppler effect. Exactly, and until an experiment is done which eliminates all other driver non-linearities an experiment hasn't been done. Bob -- "Things should be described as simply as possible, but no simpler." A. Einstein |
#61
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Randy Yates wrote:
ruffrecords writes: Randy Yates wrote: ruffrecords writes: PenguiN wrote: The sound produced by the speaker happens because the speaker is driven None of those approximates in any way, or is a valid anology for a loudspeaker producing a complex waveform that comes from only one source, the complex electrical waveform driving the speaker motor. All the other anologies have two sources, one for the low frequency motion and one for the high frequency sound, NOT a valid anology for what happens when a speaker reproduced a complex waveform. What if we take this to the extremes with a thought experiment: Picture the largest loudspeaker in the universe sitting outside somewhere. It's so big that it has a maximal excursion of several feet. Now picture a very low bass signal played on that speaker at almost maximal volume. The speaker cone is vibrating in-out-in-out-in-out. Now add to that signal a small, high pitched, low amplitude waveform. The two waveforms are added together so that it seems like the higher pitched wave is "riding on top of" the bass wave. What gets added are the instantaneous pressures. The air pressure produced is exactly the same as two separate speakers at the two frequencies. There is no such thing as doppler distortion. Consider this gedanken: Place a 4-inch speaker on the cone of a 14-foot speaker. Now, the two speakers are fed different signals. Consider this. place a 14ft speaker next to a 4inch speaker and feed them different signals. Is there Doppler? No Hey man, stay stupid - see if I give a ****. Nothing stupid about it. If both systems are linear then they will work in an identical manner. Ian |
#62
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"ruffrecords" wrote in message
Arny Krueger wrote: "ruffrecords" wrote in message PenguiN wrote: As far as our super-excursion speaker is concerned, the location that's generating the high pitched sound is moving forward and backward several feet. No it isn't. This is the flaw in all the doppler distortion arguments. If all the explanations for Doppler distortion are wrong, where does all of the FM we measure come from? Why does it correlate well with the *incorrect* theoretical predictions? To produce FM there needs to be a non-linearity. Not really. A nonlinearity produces AM. FM is exactly what Doppler distortion produces. If you detect FM there is a good chance a non-linearity exists. If you do the math, nonlinearities can't produce FM distoriton. You need something that operates in the time domain, not the amplitude domain. But it is not due to the Doppler effect. |
#63
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ruffrecords writes:
If both systems are linear then they will work in an identical manner. That statement is absolutely correct, just as "If I am pregnant, then I am a female." is absolutely correct. -- % Randy Yates % "Maybe one day I'll feel her cold embrace, %% Fuquay-Varina, NC % and kiss her interface, %%% 919-577-9882 % til then, I'll leave her alone." %%%% % 'Yours Truly, 2095', *Time*, ELO http://home.earthlink.net/~yatescr |
#64
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Bob Cain writes:
ruffrecords wrote: To produce FM there needs to be a non-linearity. If you detect FM there is a good chance a non-linearity exists. But it is not due to the doppler effect. Exactly, Not. Get a clue, people. Doppler is a *PHYSICAL PHENOMENOM* that WILL happen whether or not you decide it can WHENEVER a sound wave source and observer are moving relative to each other. Period. This isn't open for debate. -- % Randy Yates % "Though you ride on the wheels of tomorrow, %% Fuquay-Varina, NC % you still wander the fields of your %%% 919-577-9882 % sorrow." %%%% % '21st Century Man', *Time*, ELO http://home.earthlink.net/~yatescr |
#65
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"ruffrecords" What gets added are the instantaneous pressures. The air pressure produced is exactly the same as two separate speakers at the two frequencies. There is no such thing as doppler distortion. Ian ** Ian is another who cannot walk and chew gum at the same time. .......... Phil |
#66
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"Phil Allison" wrote in message ... "Porky" The sound produced by the speaker happens because the speaker is driven by a single complex waveform, thus there is a single source for the sound. The sound that comes from a train whistle is generated by the whistle, and the motion imparted to the whistle comes from the train's motion, two separate sources. ** WRONG !!! There is only one source of sound in both cases. Case 1 = the cone. Case 2 = the whistle. If you move the whistle back and forth in a manner approximating that of a speaker cone, you still have two sources, the whistle's sound and the mechanical vibration of the whistle, if you mount the whistle on the speaker cone, you have two sources, that driving the cone and that coming from the whistle. ** I told you to lay off that damn weed !! None of those approximates in any way, or is a valid anology for a loudspeaker producing a complex waveform that comes from only one source, the complex electrical waveform driving the speaker motor. ** The SOURCE source of any sound is the vibrating object or air column. All the other anologies have two sources, one for the low frequency motion and one for the high frequency sound, ** Simply not relevant. NOT a valid anology for what happens when a speaker reproduced a complex waveform. If you don't get that, then perhaps it is you who should "lay off the weed". ** There is nothing rational anywhere in your posts to get. You aren't going to get it until you can differentiate that which comes from two or more separate simple driving sources and that which comes from a single complex driving source ** Totally false distinction. It exists only in the words. BTW, I never said anything about a cone's motion being prodiuced by sound. I said "a speaker reproducing a complex waveform". ** Quote: " Even moving the whistle back and forth in approximation of a moving speaker cone is not a valid anology, because the whistle's back and forth motion is not generated by the sound coming from the whistle, as it would be in a speaker reproducing a complex waveform. " ** Yes you did, then deceitfully snipped it. In the first place, I don't go drugs of any kind, including weed and alcohol, and in the second place if you don't see the difference between providing all forms of motion involved (whether they produce sound or not) with one complex source, and providing the different forms of motion (whether they produce sound or not) with multiple simple sources, then any conclusion you may come to is going to be fundamentally flawed, and all your flippant answers aren't going to change that. |
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"PenguiN" wrote in message om... The sound produced by the speaker happens because the speaker is driven None of those approximates in any way, or is a valid anology for a loudspeaker producing a complex waveform that comes from only one source, the complex electrical waveform driving the speaker motor. All the other anologies have two sources, one for the low frequency motion and one for the high frequency sound, NOT a valid anology for what happens when a speaker reproduced a complex waveform. What if we take this to the extremes with a thought experiment: Picture the largest loudspeaker in the universe sitting outside somewhere. It's so big that it has a maximal excursion of several feet. Now picture a very low bass signal played on that speaker at almost maximal volume. The speaker cone is vibrating in-out-in-out-in-out. Now add to that signal a small, high pitched, low amplitude waveform. The two waveforms are added together so that it seems like the higher pitched wave is "riding on top of" the bass wave. As far as our super-excursion speaker is concerned, the location that's generating the high pitched sound is moving forward and backward several feet. Fundamental flaw in the logic, the higher pitched signal is not "riding on" the lower pitched signal, they are combined to produce a complex waveform driving the speaker. If you still don't believe that this scenario validates the train-whistle analogy, why not make the bass waveform move at the speed of, oh say a train, and have the high pitched signal on top of it be, oh say the sound of a whistle. Doesn't apply, the train and whistle are supplied by two separate sources of energy. The scenario described in this thought experiment would *certainly* produce doppler shift in the higher signals. If you made the bass carrier sound low enough frequency and loud enough, you would even be able to hear the weeeooohhweeeoooh modulation of the higher frequency as the source of that sound (the surface of the speaker cone) is moving towards and away from you. It follows reasonably that this also happens with regular speakers, but to a lesser extent. Once again, comparing two separate sources of motion (the train and the whistle) provided by two separate sources of energy, to one complex motion source provided by one single complex source of energy (the signal driving the speaker motor) is comparing apples to oranges. The question of whether it's a relevant, measurable, or hearable distortion is a separate issue from whether it physically exists. Agreed, but in order to reach any valid conclusions, one must stop comparing apples to oranges! |
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"Porky" "Phil Allison" ** Yes you did, then deceitfully snipped it. In the first place, I don't go drugs of any kind, including weed and alcohol, and in the second place if you don't see the difference between providing all forms of motion involved (whether they produce sound or not) with one complex source, and providing the different forms of motion (whether they produce sound or not) with multiple simple sources, then any conclusion you may come to is going to be fundamentally flawed, and all your flippant answers aren't going to change that. ** This little piggy cannot trot and chew gum at the same time. ............ Phil |
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"Porky" Agreed, but in order to reach any valid conclusions, one must stop comparing apples to oranges! ** This litle piggy cannot trot and chew rotten fruit at the same time. ............... Phil |
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"Randy Yates" wrote in message ... Bob Cain writes: ruffrecords wrote: To produce FM there needs to be a non-linearity. If you detect FM there is a good chance a non-linearity exists. But it is not due to the doppler effect. Exactly, Not. Get a clue, people. Doppler is a *PHYSICAL PHENOMENOM* that WILL happen whether or not you decide it can WHENEVER a sound wave source and observer are moving relative to each other. Period. This isn't open for debate. This whole argument is based on the wrong assumption that the high frequency source is "riding on" the low frequency source like a whistle on a train. It is NOT! Both sounds are being produced simultaneously by the complex electrical waveform driving the speaker cone which moves in accordance. Assuming that the speaker is being driven within its linear limits, the cone's motion accurately follows the driving signal, and it is a linear system. Forget the train/whistle anology, it is not an accurate representation for what goes on with a speaker, period! |
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"Phil Allison" wrote in message ... In the first place, I don't go drugs of any kind, including weed and alcohol, and in the second place if you don't see the difference between providing all forms of motion involved (whether they produce sound or not) with one complex source, and providing the different forms of motion (whether they produce sound or not) with multiple simple sources, then any conclusion you may come to is going to be fundamentally flawed, and all your flippant answers aren't going to change that. ** This little piggy cannot trot and chew gum at the same time. Are you kidding? I can drive a racecar while chewing gum and simultaneously contemplating the possibility that a speaker can generate Doppler distortion while producing multiple tones when driven by a single complex waveform, and at the same calculating the probibility (approx 83.762%) that you are the one who is smoking weed.:-) |
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"Phil Allison" wrote in message ... "Porky" Agreed, but in order to reach any valid conclusions, one must stop comparing apples to oranges! ** This litle piggy cannot trot and chew rotten fruit at the same time. Ah, yes, but Phil can, in fact, he does it all the time. Unfortunately the rotten fruit has fermented and contains a high level of alcohol, which has severely unbalanced Phil's mental process.:-) |
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"Porky" writes:
"Randy Yates" wrote in message ... Bob Cain writes: ruffrecords wrote: To produce FM there needs to be a non-linearity. If you detect FM there is a good chance a non-linearity exists. But it is not due to the doppler effect. Exactly, Not. Get a clue, people. Doppler is a *PHYSICAL PHENOMENOM* that WILL happen whether or not you decide it can WHENEVER a sound wave source and observer are moving relative to each other. Period. This isn't open for debate. This whole argument is based on the wrong assumption that the high frequency source is "riding on" the low frequency source like a whistle on a train. It is NOT! Oh, but it is. That is precisely what is happening. Both sounds are being produced simultaneously by the complex electrical waveform driving the speaker cone which moves in accordance. True, and how does that refute that there is no Doppler? Before it ever gets to a speaker, such an electrical signal will have the characteristic of the high frequency wave "riding" on top of the low frequency wave. You will see it on a scope. Input that to a speaker and you will see precisely the same thing if you observed a plot of speaker cone displacement versus time. Assuming that the speaker is being driven within its linear limits, the cone's motion accurately follows the driving signal, True. and it is a linear system. FALSE! Well, at least if you define "it" to be the entire composite system from the speaker's electrical input to the acoustic receiver's input. In that case, it ain't linear. That's the whole point. The physics of what happens between the speaker cone and the acoustic observer are such that Doppler will take effect. Now how *much* Dopper is another question, but the effect will be there for sure, just as two masses will experience an attraction based on the inverse square law (m1*m2/r^2). Forget the train/whistle anology, it is not an accurate representation for what goes on with a speaker, period! Proof by assertion? -- % Randy Yates % "Ticket to the moon, flight leaves here today %% Fuquay-Varina, NC % from Satellite 2" %%% 919-577-9882 % 'Ticket To The Moon' %%%% % *Time*, Electric Light Orchestra http://home.earthlink.net/~yatescr |
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On Mon, 16 Aug 2004 21:57:16 -0500, "Porky" wrote:
"PenguiN" wrote in message . com... If you still don't believe that this scenario validates the train-whistle analogy, why not make the bass waveform move at the speed of, oh say a train, and have the high pitched signal on top of it be, oh say the sound of a whistle. Doesn't apply, the train and whistle are supplied by two separate sources of energy. Have two amplifiers, one for the low frequency connected to the speaker through an inductor, another amp outputting the high frequency connected to the speaker through a capacitor. Thus the low and the high are supplied by two separate sources of energy. Actually, isn't the train whistle powered by steam from the same boiler that powers the wheels, moving the train? What's up with that? But seriously, for Bob and other anti-doppler-distortion folks, how does cone-and-frame movement cause doppler while cone movement only does not? What is it about the frame that causes doppler? If you put the speaker on a shaker table, run 1kHz and 50 Hz through the speaker, move the shaker table at 50 Hz opposite the phase to the speaker so the cone only moves at the 1kHz rate with respect to the air, will it generate doppler distorion? According to my understanding of Bob's position, it should. ----- http://mindspring.com/~benbradley |
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Porky wrote: Are you kidding? I can drive a racecar while chewing gum and simultaneously contemplating the possibility that a speaker can generate Doppler distortion while producing multiple tones when driven by a single complex waveform, and at the same calculating the probibility (approx 83.762%) that you are the one who is smoking weed.:-) ROTFLOL! :-) Bob -- "Things should be described as simply as possible, but no simpler." A. Einstein |
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ruffrecords wrote: super-excursion speaker is concerned, the location that's generating the high pitched sound is moving forward and backward several feet. No it isn't. This is the flaw in all the doppler distortion arguments. What he said. Bob -- "Things should be described as simply as possible, but no simpler." A. Einstein |
#77
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ruffrecords wrote: Nothing stupid about it. If both systems are linear then they will work in an identical manner. What he said. Bob -- "Things should be described as simply as possible, but no simpler." A. Einstein |
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Arny Krueger wrote: If all the explanations for Doppler distortion are wrong, where does all of the FM we measure come from? Why does it correlate well with the *incorrect* theoretical predictions? What theoretical prediction might that be? I've yet to see a theory for "Doppler distortion" that predicts. Odd, that. Bob -- "Things should be described as simply as possible, but no simpler." A. Einstein |
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Randy Yates wrote: Not. Get a clue, people. Doppler is a *PHYSICAL PHENOMENOM* that WILL happen whether or not you decide it can WHENEVER a sound wave source and observer are moving relative to each other. Period. This isn't open for debate. Randy has spoken. Without one shread of a predictive theory. Odd, that. Bob -- "Things should be described as simply as possible, but no simpler." A. Einstein |
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Porky wrote: This whole argument is based on the wrong assumption that the high frequency source is "riding on" the low frequency source like a whistle on a train. It is NOT! Both sounds are being produced simultaneously by the complex electrical waveform driving the speaker cone which moves in accordance. Assuming that the speaker is being driven within its linear limits, the cone's motion accurately follows the driving signal, and it is a linear system. Forget the train/whistle anology, it is not an accurate representation for what goes on with a speaker, period! What he said. Is this the same Porky that I've argued with about _so_ many things? Bob -- "Things should be described as simply as possible, but no simpler." A. Einstein |
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