Re: high-frequency hearing in humans

[Andrew McGuiness <andymcguiness@xxxxxxxxxxxx>]

Others on the list will be more qualified to comment on this than I am, but could the audible difference between sampling rates be due (at least in part) to differences in phase resolution? Frequencies at the Nyquist limit for a sampling rate will be reproduced with only two possible phase positions; frequencies a little lower will have more, but not the full discernible range of phase difference. Can't we hear phase differences within a few microseconds? A 44.1kHz sampling rate will have a phase resolution of roughly 20 microseconds. As I understand it, phase differences at frequencies approaching the Nyquist rate are translated into level differences (eg. a frequency component at the Nyquist rate, sampled just after a positive-going zero crossing will be recorded at a low level, and the phase information will be reduced to 'positive'); in practice, oversampling compensates for the loss of level, but not for temporal resolution of phase.

Andy

 

Dr Andy McGuiness
andymcguiness@xxxxxxxxxxxx
http://open.academia.edu/AndyMcGuiness

Date:    Fri, 4 Feb 2011 07:41:39 -0700
From:    "Maher, Rob" <rmaher@xxxxxxxxxxxxxxx>
Subject: Re: High-frequency hearing in humans

Although the DSP portion of an oversampled system has precisely defined
performance characteristics, I remain highly skeptical that the
transducers and analog electronics available to most users have ever
been evaluated in any meaningful way outside the 20-22kHz bandwidth.  I
encourage everyone to be cautious about drawing cause and effect
conclusions for anecdotal reports.  It may well be that your colleague
is hearing something, but the "how" and "what" is not likely to be
revealed by introspection alone.

Rob