Re: cochlear wave travel time

[Matt Flax <flatmax@xxxxxxxx>]

Hi Pawel,

The answer to your question depends on your belief of how the inner ear 
operates. The reason is because you are looking at neural stimulation 
and NOT simply cochlear waves.

Do you believe in active travelling waves, active compression waves or 
other mechanisms ?

Either way, the time taken for mammals is expected to be of similar 
order between species.

If you believe in active travelling waves, then the delay to 
stimulation of the nervous system depends on forwards and backwards 
travelling waves passively and actively generated ... there are a large 
number of papers treating that ... search for articles which mention 
forward and reverse travelling waves. Due to the time taken to reach the 
apex of the cochlear (low freq.) they will generally be longer 
intervals then basal high frequency locations.

If you believe in active compression waves, then you are in luck as only 
last week the first physiological model treating the compression wave 
cochlear amplifier was released on the Cochlear Amplifier e-mail list :
http://cochlearamplifier.dyndns.org/pipermail/cochlear-amplifier/2008-July/000332.html
The archives for that list can be reached from here :
http://cochlearamplifier.dyndns.org/cgi-bin/mailman/listinfo/cochlear-amplifier

That model of the compression wave cochlear amplifier suggests that time 
to neural reception is only of the order of the passive travelling wave.

Of you believe in other models, then you will need to seek more 
information depending on which model you are looking further into.

Either way, if your stimulating signal is below about 60 dB SPL, you 
will need more information from the model or point of view you wish to 
apply as reception of soft sounds requires some form of amplification 
within the inner ear for reception. If your stimulating signal is above 
60 dB SPL (roughly) then there is larger likelihood that the signal will 
be received simply and directly from the passive travelling wave 
cochlear amplifier.

Hope that information helps !

Matt

On Wed, Jul 23, 2008 at 12:03:19PM -0400, Pawel Kusmierek wrote:
> Dear list,
> 
> would you kindly suggest references on cochlear travel time that would
> allow me to find out when the high-frequency-induced signal becomes
> available for the nervous system in comparison to
> low-frequency-induced signal? Data from rhesus cochlea would suit me
> best, but any other animal that can be reasonably assumed to be
> similar the monkey in this respect would be good for me too.
> 
> Thank you,
> 
> Pawel
> 
> -- 
> Pawel Kusmierek PhD
> Department of Physiology and Biophysics
> Georgetown University Medical Center
> The Research Building WP23
> 3970 Reservoir Road NW
> Washington, DC 20007
> phone: +1 202 687-8851 or 8028, fax: +1 202 687-0617