Translation of sound into Neural signals?
Didier A. Depireux
didier at rai.isr.umd.edu
Mon Apr 15 10:34:28 EST 2002
John Leonard <jleonard2 at si.rr.com> wrote:
> About how far does this stand, being able to read efferent neural
> signals coming from the Inner Ear Cochlear Nerves and reconstructing the
> sounds which produced them?
There are about 10 auditory nerve fibers per inner hair cell, and they lock
to the waveform of the stimulus up to about 1.5-2.5 kHz (depending on who
you talk to). So for the frequencies below about 2kHz, you can reconstruct
the incoming sound exactly. For higher frequencies, you mostly have access
to the envelope modulations, and not to the phase of the constituent tones,
so there you can recontruct a similar sounding waveform, but not the exact
All this is up to an overall loudness factor. Given the active processes in
the cochlea, including feedback from the brainstem, I don't know whether you
could really tell the exact loudness that was presented to the ear if you
presented a single sound and asked "Was that a 45dB or a 50dB sound?".
Didier A Depireux ddepi001 at umaryland.edu didier at isr.umd.edu
685 W.Baltimore Str http://neurobiology.umaryland.edu/depireux.htm
Anatomy and Neurobiology Phone: 410-706-1272 (off)
University of Maryland -1273 (lab)
Baltimore MD 21201 USA Fax: 1-410-706-4724
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