< > Still, Sony held out for a higher rate since psychoacoustic research had
shown that frequencies well above the so-called 20 KHz maximum affected one's
impression of a sound. (I additionally recall they used solo piano as a test
case.) <
Audio mythology, I suspect. The only research I've seen on that was
questionable. I'm ready to be corrected if you have the studies. >
I read the research & communicated briefly with a prof at Cal Tech who was
doing extended bandwidth studies based on the spectrum of a trumpet fitted with
a Harmon mute. He did show that a majority of the energy exists above human
hearing, & that selectively removing some of those out of band harmonics was
perceptible to some trained ears. But his agenda was to show the superiority of
analog over digital, so his methodology seemed suspect to me.
Rupert Neve used to have a simple, though not scientifically controlled,
demonstration, which he used as his justification for extended bandwidth needs.
He would play a sine wave at the upper end of a person's perception, 15kHz or
maybe higher. The respondent would agree that it was audible. Then Neve played
a square wave at that same frequency. The harmonics in the square wave would
obviously all be entirely beyond ones supposed 20kHz limit to perceive. Yet
invariably the respondents would be able to identify the square wave as audibly
distinct from the sine wave, even though theory would tell us that only the
fundamental (a sine wave) of the square wave should be audible. Neve arrived at
this test after an engineer told him that one module on a Neve desk was
malfunctioning compared to the others. The engineer could hear a difference in
that channel, & nobody else could. Tests revealed that that channel was
oscillating at something like 60kHz. Perhaps it's audio mythology, but having
come from the mouth of Rupert Neve I'm inclined to give it credence.
Scott Fraser
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