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phase-locking in cochlea

Jeffrey Sirianni audioman at HCTC.NET
Mon Dec 2 00:50:27 EST 1996

Bill Simpson <wsimpson at uwinnipeg.ca> writes:

>Several fairly old papers (e.g. Evans, 1975; Rose et al 1968) show that
>cochlear nerve fibres fire in a phase-locked way. They fire on the peaks.
>I was wondering if there are recent papers discussing how this is used 
>for the coding of frequency in the brain.
>A simple-minded way is to say the brain just uses the minimum delay
>between spikes as the period (and freq=1/period). Since the fibres don't
>fire on every peak, will get a variety of delays between spikes, but all
>delays will be multiples of the smallest delay (e.g. 10, 20, 30, 40, 50
>ms). So another approach is to assume you have series {a*1, a*2, a*3,...}
>where a is period (in practice a will vary a bit). Other more
>sophisticated ideas are possible.

Your understanding of phase-locking at the auditory nerve level is correct,
except when you try to explain frequency excoding for frequencies above 2000
Hz, where phase-locking degrades (I may be off here and would appreciate any
comments to correct my number of 2000 Hz).

{Jogging the memory banks....}

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