On Sat, 18 Sep 2010 07:35:55 -0700, Arny Krueger wrote
(in article ):
"Audio Empire" wrote in message
Well, off the top of my head I know that Bell Labs did a
number of tests during the 1930's of these phenomenon,
and Harry Olsen of RCA Labs did some in the 1940's and
seems to me that I recall that Benjamin Bauer of CBS Labs
did similar studies in the 1950s or 1960's. I've been in
audio A LONG TIME and have read thousands of articles on
this and other subjects. But the biggest ally for my
assertion is common sense. If something sounds distorted,
or noisy in a way that bothers a listener (and this could
be subliminal) he or she is not going to listen to it for
long. Of course, gross distortions will get an immediate
reaction and people will stop listening, but more subtle
forms of distortion may not drive the listener away
immediately, but could do so over a long listening
session.
This is all true. The proof of it is modern life. If you know what the
technical performance of mainstream audio was like in 1930, 1960, 1990, and
2010, there has been a steady reduction of audible noise and distortion. I'm
talking about the audio heard in theatres, homes, businesses.
Yep. In most cases, this is actual fact. If you look at network videotape
performances from the '60's and '70's, you' will notice that the audio is not
clean as it is on later video performances. Certainly modern cinema sound is
head and shoulders above that available in the past. Even really big budget,
wide-screen productions upon which was lavished every advantage that the
studios could bring to bear (Ben-Hur, Lawrence of Arabia, How The West Was
Won) had sound that is primitive by today's standards for even
run-of-the-mill "bubble-gum" productions.
One Forum that I looked had a respondent go so far as to
say:
"For me many factors contribute to listening fatigue. One
of the main ones is CD Red Book quality audio which has
less low level information than all but the worst analog
recordings, if that.
This is a gigantic misapprehension. In fact the inverse is true, and not by
just a little. Redbook CD audio has an average of 20-30 dB more low level
audio than the best analog recordings.
Yep.
Meaning there is just less
involvement possible with the music, so the recording
flaws stand out more.
The reality is that CD's don't mask recording flaws nearly as well as
analog, particularly LP recording does.
Well, there are really BAD sounding LPs out there and really BAD sounding CDs
as well. But the bad CDs sound bad in a different way than do bad LPs (!)
I was semi-enthusiastic about SACD
and DVD Audio for a while wrt to resolving the low level
resolution and brick wall cutoff problems with Red Book,
but it appears they are going by the wayside."
http://www.diyaudio.com/forums/multi...stening-fatigu
e-
14.html
SACD did add another 20 dB or so of low level detail to redbook CD audio,
but due to problems with other parts of the record/playback chain, the
technical enhancement was practically moot. DVD-A added almost another 20
dB to what SACD provides, but now we are talking moot squared.
The DVD-A people squandered that advantage by not standardizing on one set of
sample rates and bit depths for stereo (24/192) and one set for surround.
When one bought a DVD-A, one never knew what one was getting unless one read
the label VERY carefully. Now Blu-Ray offers the record companies another
chance to screw it up once more with at least EIGHT different primary audio
specifications being supported.
Not so sure that I buy that, but it is a thought.
Just a cursory search on Google found this description on
Wikipedia:
"Listener fatigue occurs when the ear tunes out unwanted
noises and focuses on the wanted ones. When listening to
music for example, the speakers may give off an unwanted
hissing noise that the person has to focus out, causing
"Listener Fatigue".
Add to hiss the incessant tics, pops, flutter, wow, inner groove distortion,
etc and the relevant question becomes "Why isn't listening to LPs more
fatiqueing?" For most of us, it is.
Well, for SOME of you it is. Remember, people don't actually make a choice
between CD and LP, they buy what's available that has THEIR music on it and
what's available are MP3 downloads and CDs.
This is an extension of the quantifiable psychological
perception of sound, adding time-variance effects.
This subject is not well covered on the internet because
most of these research papers haven't been posted.
However, Howard Tremaine's "Audio Cyclopedia" discusses
the subject and the seminal work by Read and Welch, "From
Tinfoil to Stereo" mentions listener fatigue modeling
done at Bell Laboratories in 1933. This battery of tests
tended to show that some types of distortion cause
greater listening fatigue than do others. For Instance,
Harmonic distortion in amplifiers is more well tolerated
than it is in signal sources such as phonograph records
and radio reception, but that intermodulation distortion
was poorly tolerated wherever it occurred and very small
measured amounts is clearly audible.
The fallacy here is that there are equipment properties called "Harmonic
Distortion (THD)" and "IM Distortion" and that they are somehow distinct
from each other. Reality is that equipment has nonlinear (and linear)
distortion , and that THD and IM are abstract ways to measure nonlinear
distortion. Every real world instance, every piece of real world audio gear
that produces nonlinear distoriton will product measurable amounts of both
THD and IM, if you use appropriate measurement techniques.
That's true to a degree, but different types of distortion affect people in
different ways. Some types of distortion (I guess we should say distortion
that arises from different causes) people don't mind so much, and other types
of distortion, that even in minute amounts, cause listening distress. For
instance, it has been found that the human ear is quite insensitive to what
we call THD in amplifiers. Some amps produce as much 2% BEFORE clipping, and
yet some of these amps "listen" so well that they actually gained cult status
as the best there was in their day. I'm thinking specifically here of a
French tube amp (forget the brand) from about 10 or 15 years ago that was the
rave of the high-end set. At high-wattage, output it produced more than 2%
THD, yet even on crescendo's nobody could detect it by listening. Yet small
amounts of IM, which is mostly made up of odd harmonics is very noticeable
because it is often uncorrelated.
The amount of nonlinear distortion in ca. 1933 phonograph records and radio
receivers was horrific. Some of the amplfiers of the day were not nearly as
bad. There were no DBTs in 1933 and what we would call clean signal sources
were practically unheard of. Perceptions of which equipment was sonically
clean and which was sonically dirty was therefore highly flawed.
No doubt, but the basic principles of what people will and won't tolerate
still apply.
My only real assertion here is that distortion on some
level and of some kinds cause listener fatigue.
The "human factors" contributions to fatigue are very important. Attitude,
preferences and mental circumstances have a lot to do with it.
Yep.
This is
well known. CDs have LESS distortion than analog sources
and should therefore NOT cause listening fatigue.
This is true until you start considering the non technical human factors.
Of course.
That it
does for some people is a fact, that I don't even pretend
to understand. I don't think anybody does.
I've presented viable explanations that are based on modern human factors
reasearch. YOu've got to look at the big picture and admit that you are not
totally removed from your biases and sentimental feelings.
Oh, I Know that probably better than most. But remember Mr. Kruger, with all
due respect, that blade has two edges.