Re: What is the price for hearing

<ed@mdsp.com> wrote in message
news:t30ks3hffb71efchpb1ncar3udarsjbia4@4ax.com...
> Ken:  Physiology of the Peripheral Auditory System  101:

>
> It is believed that the OHC's attenuate the loud passages protecting
> the IHC's from excessive vibration.
>

>>Interesting about the guard hair cells. In the process of being
>>assessed for CI I learnt that the hairs responding to high frequencies
>>are nearer to the cochlea entrance (which, I assume, is why high
>>frequencies are, generally, lost first. But are you saying that these
>>front-line hair cells have special additional functions? Or just that,
>>as they are destroyed, the front-line moves back?


Not exactly, Ed, but close. Work by Peter Dallos and others show that the
outer hair cells tune the vibratory response, in a fashion similar to the
way The Beach Boys keyboardist played the theremin in "Good Vibrations", so
that the sensory cell, the inner hair cell, can send the tuned response on
to the higher level central mechanisms. The OHCs expand and contract
hundreds of times a second. Since they are not muscle contractions, but
something else, there is no buildup of lactic acid and thus, no diminishing
of the response over time. If the OHCs are destroyed, it is hoped that
simple loudness increase will compensate by delivering a larger response to
the IHC, but as any hearing aid wearer will tell you, it just ain't the
same. Maybe it's loudness alone which is tuned, but, probably not.
Most if not all failures with aids can be attributed to the loss of this
fine "motor" control exercised by the OHCs.


Dr. Ridenhour
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Poster (02.03.2008 20:41)