Re: High frequency sensitivity

[Dick Duda <DUDA@xxxxxxxxxx>]

> Does anyone know any studies that point to frequencies >
> 20kHz affecting perception (maybe of transients rather
> than continuous tones).
> Does anyone have an opinion?

The debates over bandwidth needed for high-fidelity sound reproduction
are long standing and unlikely to be resolved to everyone's satisfaction
in the near or even the distant future.  However, I will note that I
have found the commercial 44.1-kHz sampling rate to be marginal in
studying binaural hearing and spatial localization.

A number of studies have shown that normal listeners can localize
sources in azimuth to about 2 degrees, and can reliably detect changes
in position (the minimum audible angle) to about 1 degree (for example,
see A. W. Mills, "Auditory Localization", in J. V. Tobias,
Foundations of Modern Auditory Theory, Vol. II, pp. 303-348 (Academic
Press, NY, 1972)).

To the extent that this performance is dependent on detecting interaural
time differences, it implies the ability of the auditory system to
detect shanges in arrival time as small as 9 usec.  At 44.1 kHz, the
sampling interval is about 22 usec, making it hard to create digital
audio test signals with smaller interaural time shifts to test the
limits.

Of course, the ability to detect a 10-usec difference in arrival time
does not imply that the auditory system has a 50-kHz Nyquist frequency,
and I do not believe that this would have any appreciable effect on home
entertainment systems, even for listeners with "golden-ears" (which
excludes me).  However, I often wish that the sampling rate were closer
to 100 kHz for my own work.

Dick Duda
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