From: utzoo!decvax!harpo!seismo!hao!hplabs!sri-unix!VaughanW.REFLECS@HI-Multics
Newsgroups: net.physics
Title: Re: Digital Vs. The Audiophile.
Article-I.D.: sri-unix.4897
Posted: Fri Dec 17 16:29:23 1982
Received: Sun Dec 19 07:09:49 1982

A few random comments:

1.  Throughout the Sixties, a lot of audiophiles complained that
transistor amplifiers didn't sound as good as tube amplifiers.  They
were uniformly ridiculed by people who claimed that steady-state
frequency response charts told the whole story, and on the basis of
these charts, transistors were better than tubes.

I don't really need to remind anyone that in the late Seventies the
audiophiles were proved to have been correct, when TIM (transient
intermodulation) distortion was discovered.  Although the 1965-vintage
transistor amplifiers had far less harmonic distortion than a
1959-vintage tube amplifier, their TIM distortion was orders of
magnitude higher.

The lesson is that good steady-state figures are necessary but not
sufficient.

2.  The human ear is not sensitive to sinusoidal waveforms much above
18kHz.  If we believe in Fourier transforms (which is much like
believing in 1+1=2: it's ordinary mathematics), we may conclude that the
ear is also insensitive to repetitive signals of any waveform and whose
repetition rate is significantly above 18 kHz.

But Fourier transforms don't deal with transients.  A waveform must be
repetitive for Fourier analysis to apply.  Besides, the ear is known to
be exquisitely sensitive to very small phase diferences in arriving
waveforms: One can accurately, with closed eyes, locate an arriving
sound \in a vertical plane/ by using the differential delay lines built
into the external ears (ref.  Scientific American articles some years
ago) - where the differences in wavefront arrival time may be measured
in microseconds!  So much for the Fletcher-Munson curve.

3.  The mathematical analysis of waveforms is a relatively
well-understood field.  Not so the perception of sound, which involves
elements of psychology and the organization of neural networks and
processing within the brain.

We often make the mistake of identifying two things that match only
partially; thus, we identify color with frequency of light (a false
identification according to the Land theory of color vision), and we
identify pitch with frequency of sound (a fallacy familiar to any piano
tuner).  Why, then, should we identify perceived quality of sound with
mathematical distortion of the sound's waveform?