What Can We Hear?
On Wed, 16 May 2012 16:41:19 -0700, Gary Eickmeier wrote
(in article ):
"Audio Empire" wrote in message
...
The human ear is a sensitive tool, no doubt about it. Unfortunately, it is
also an interpretive tool. There is no sound preception without the brain
and
the brain brings with it a lifetime of experience, preconceptions, and
personal preferences. It applies these factors to everything we hear and
they're difficult to overcome. In fact, I'd go so far as to say that we,
as
individuals, can't overcome them. We are going to hear what we want to
hear
or what we expect to hear. The only way around this is to take human bias
out
of the equation with tests that are either totally objective (such as
measurements using instrumentation) or by taking part in listening tests
which remove as much of the human propensity for self-delusion as possible
and relying on the statistical results. To paraphrase an old adage: he who
trusts his own ear/brain interface to judge audio qualities is a fool.
Careful. Our ears are the final arbiter in audibility of effects. You just
have to keep the brain at by with DBT. What I mean by hard-nosed listening
is trying to keep the overactive imagination out of the discussion and being
honest about what you are hearing. If you can tell that the sound is coming
from a pair of speakers, and you are not being fooled into thinking "you are
there," then admit it and try for some improvements.
I think I just said that...
Phase anomalies are real. You can measure them and you can easily hear
their
effects. All one has to do is walk past a stereo pair of speakers that are
wired out-of phase to instantly hear the results. You can also take a
recording made with a pair of spaced omnis and sum the two channels to
mono
to immediately hear (and see, on an oscilloscope) some of the instruments
go
away.
Monophonic phase response is not audible, and wasting time time aligning
drivers is a dead end.
That's irrelevant to my comments. In stereo, phase differences are part of
what constitutes "channel separation" and therefore imaging. Also, there is
nothing of a "waste of time" about making sure all of your speakers are
in-phase and it's easy to hear when they are not. Yet, if I had a dollar for
every stereo store's demo room I've entered only to say to the salesperson
"Your speakers are out of phase", I could have a really good steak dinner at
Ruth's Chris!
Also, the fact that spaced omni's aren't phase coherent is one of the reasons
why Telarc's classical recordings never imaged as well as they should. I'd
say phase is very important. OTOH, I've never heard any REAL advantage to
"time aligned" drivers in speakers. It might be theoretically important, but
the difference certainly doesn't reach out and grab you.
I have to disagree here. While you are correct about being able to tell,
even
blindfolded, the approximate size of a room you're in, you are wrong about
the results. It is possible to make a small room sound good much more
easily
than it is possible to make a large room sound good. Small rooms have all
the
characteristics that you mention (and then some) but they are all fairly
controllable.
Would you agree that you cannot make a room sound bigger than it actually is
by playing a sound recorded in a larger room?
Of course you can't. However, you can use a DSP based playback reverb system
(such as those made by Lexicon) and speakers placed in the back of a smallish
room and by choosing the correct amounts of delay and reverb make the room
sound bigger. Like I said, a small room's anomalies are controllable by
various means.
Again you are grossly oversimplifying. Power, in and of itself is merely a
means to an end. The end is moving air. The more air you can move the more
realistically an audio system will load the room with sound and the amount
of
air any speaker can move with a Watt of electrical power from an amplifier
is
determined by two things: the efficiency of the speaker and the volume of
the
space one is trying to fill.
and so on. Obviously, all I mean is acoustic power. I don't care how you get
there, with normal speakers and a lot of power, or efficient horn speakers
and less powerful amps, just mean how loud can it go undistorted.
Then you should have said acoustic power. As you wrote it, it pertained to
amplifier power. That's all I had to go by in my response.
Actually, it is a pair of windows (in a traditional two-channel stereo
setup). They're called your speakers. Their job is to recreate, as
accurately
as possible, the electrical signal fed to them. Ideally, the acoustic
wavefront they produce will be exactly like the audio signal they are fed.
The problem is that's an illusive goal. It's pretty much impossible, in
fact.
We can get close, and we DO get closer all the time. but each step we take
toward that goal, gets smaller than the one before it. Taken
metaphorically,
we'll never get there.
Good illustration of a false goal. Accuracy of what compared to what?
That should be apparent. The speakers can only be accurate to what's fed them
and that's all I meant. The acoustic waveform emanating from the speakers
should look EXACTLY like the electrical signal fed to it. I.E. feed the
speakers a perfect square wave and it should produce a perfect square wave in
space - at any frequency in the audio spectrum. No overshoots, no rounding of
the flat tops of waves, no ringing. Obviously, that's impossible.
Your
statement above would indicate that you think the ideal speaker is a point
source directional jobby that has no output to the rear or sides anc can
cast all of its output directly toward your ears. That would be perfect
"accuracy" of the wavefront compared to the electrical signal fed them
I don't think that's obvious at all, and in fact, I said nothing of the sort!
The perfect speaker is, by definition, an infinitely small, omnidirectional
point source in the form of a pulsating sphere that can respond instantly to
every nuance of the signal fed to it (see above).
But stereo is not an "accuracy" process. That signal contains recorded
information from the venue that arrived at the microphones from widely
varying incident angles. I think you know what I mean. To shove all of that
recorded sound at you from just that one point in space would CHANGE the
spatial characteristics of the original to those of your speakers. So would
that be "accurate"?
Accuracy on that level is a goal. It is not an achievable goal, because the
physics of reality mitigate against it. But trying to get there (such as what
MBL is trying to do with the MB-101 MkII and their pulsating spheres) is a
worthy goal.
ther, if you
think of it as a model of the original, in which your room is the
performing
space and your speaker setup attempts to get the spatial closer to the
original, then you have a fighting chance for greater realism, but you
also
inherit the understanding that it is not an "accuracy" process, and we
can
never get all the way there. We cannot, in other words, totally get to
the
goal of a "you are there" experience but rather more like a "they are
here"
experience in which your room is the performing space and you design it
for
good sound and arrange THE BIG THREE of speaker positioning, radiation
pattern, and room acoustics to get the model closer to the live
situation.
And this would be different from two open windows onto a space where a
musical ensemble is playing, how?
Please see the next thread, "What Can We Hear?".
So what can we hear? We can hear the spatial, spectral, and temporal
characteristics of our listening room and speaker situation, or layout,
superimposed on that of the recording, and we can hear the physical size,
power, and electronic accuracy of your system. When we play back any
recording, we CHANGE the spatial characteristics of the original to those
of
our playback system and room.
That is slightly too bad, but once we understand the limitations of the
system and what can be achieved, we can stop worrying about false goals
and
start concentrating on more fruitful paths that can lead to greater
realism.
Which would be?
Getting the spatial more correct by looking at the reproduction as a model
of the live situation, rather than a "window" to another space. This, in
turn, forces you to think about "the big three" of radiation pattern, room
positioning, and room acoustics.
OK first of all, are you aware that at least 90% of all of the commercially
available classical recordings don't image anywhere near as well as the state
of the art has allowed since stereo recording began in the mid-Fifties? How
can you "get the spatial more correct" on the listening end when most record
companies can't get it right on the recording end, the end over which you and
I, as listeners have NO control?
And getting our system to be more like a model of the live situation can't be
done with two channels, but I'll let you in on something, you can get damn
close. I have symphony orchestra recordings that I have made with just two
cardioid condenser microphones mounted on a stereo "T"-bar with their axis's
90-degrees apart that image so well, that you can close your eyes and point
to every instrument in the orchestra. You can even tell that the back row of
brass is sitting up on risers and are higher than the woodwinds in front of
them! How's that for realistic soundstage. It can be done, it has been done
in commercial recordings, but it's SELDOM done. I can count on the fingers of
two hands the commercial classical recordings that I have (and I have
literally thousands both in Vinyl and CD) that image like that. You want to
go on a crusade for better sound? Start there.
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