Re:ears

[Malhomme Olivier <malhomme@infobiogen.fr>]

This is a post Sean sent me. In fact after I checked, my memory failed
me, Sean got the real story here:
That lead open the debate about possibility to "hear" over 20 kHz, was
it after effects of these frequencie we hear on lower ones doesn't
change a thing... But n its true form sthis story is anyway quite....
interesting to say the least!


>It is the story of a great  world wide known Sound Engineer (whose name

>escapes me at the time, but I can look for it) who had trouble with  a
>big Neve or SSL mixing desk (but can one still use the word "desk"?).
He
>felt something uncomfortable in the high end without being able to
>pinpoint what. In the end after testing of the unit. The people of
>(either Neve or SSL) discovered that the unit had on a few inputs, some

>bad soldering things that created a frequency peak at ... 56 KHz!

who knows what the truth is here...  but

from the rec.audio.pro FAQ:
  For example, there is an apocryphal story about Rupert Neve that
  tells of a console channel that sounded particularly "bad". It was
  later discovered that it was oscillating at some ultrasonic frequency,

  like 48 kHz. Rupert Neve is rumored to have seized upon this as
  "proof" that the ear can hear well beyond 20 kHz. However, there exist

  an entire range of perfectly plausible mechanisms that require NO
  ultrasonic acuity to detect such a problem. For example, the existence

  of ANY nonlinearity in the system would result in the production of
  intermodulation tones that would fall well within the 20 kHz audio
  band and certainly would make it sound awful. Even the problem that
  was causing the oscillation itself could lead to massive artifacts at
  much lower frequencies that would completely account for the alleged
  sound of the mixer in the complete absence of a 48 kHz "whistle."

  Whether 20 kHz is an adequate bandwidth is a debatable subject.
  However, several important facts have to be remembered. First, BOTH
  analog AND digital reproduction systems suffer from roughly the same
  bandwidth limiting. Second, digital systems using properly implemented

  oversampling techniques have far less severe phase and frequency
  response errors within the audible band. No analog storage and
  reproduction system can match the phase and response linearity of a
  digital system, both at low and high frequencies. Once those
  demonstrable facts are acknowledged, then the discussion about
  supra-20 kHz aural detectability can continue, knowing that, if it is
  demonstrated to be significant, both systems are provably deficient.

don't look at me, man, I don't write
this stuff, I just read it.

Sean Barrett