Mechanisms of hearing question

[Didier A. Depireux]

: I can't understand how a sound pressure wave could survive if its amplitude was
: less than brownian motion.

That's quite a good question mind you. I have a hard time with that too!

: Some people with severe hyperacusis (a condition where normal levels of sound
: are uncomfortable) can hear sounds with negative dB levels.  

Just to point out that zero dB is defined to be the minimum sound pressure
level that can be heard by _average_ 17 year-old males with good hearing.
It corresponds to 20 micro-Pascal rms. So it's just an arbitrary reference,
and half of those kids had thresholds down to -3 or -4 dB (at about 3-4 kHz).

						Didier

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Didier A Depireux                              didier at isr.umd.edu
Neural Systems Lab                 http://www.isr.umd.edu/~didier
Institute for Systems Research          Phone: 301-405-6557 (off)
University of Maryland                                -6596 (lab)
College Park MD 20742 USA                     Fax: 1-301-314-9920