Transfer function of human head

"I. R. Khan" wrote:
> 
> Hi all,
> 
> We are trying to make a hearing aid for profoundly deaf people. It is
> observed that if a sound signal modulated on an ultrasonic carrier is
> conducted through the bones in the human head, it is audible (and even
> understood in some cases) by profoundly deaf people. However, the exact
> phenomenon happening inside the head is not exactly known. We want to
> calculate the transfer function between the excitation position
> (position of the transmitter placed behind the ear) and the cochlea, to
> explain the phenomenon and improve the performance of our device. The
> problem is that we know the input but for the output (the sound actually
> heard), we have to depend on the human subjects and there are lot of
> differences in the data collected from different subjects. We find
> ourself stuck, and shall be extremely thankful if some one could please
> suggest a way to proceed.

It's pretty hard to guess what you might already know. 
	What I would think you would have explored is how individual frequencies
(both input and carrier) perform with individual subjects. At that level
the sound is either heard or it isn't (the subject responds or doesn't).
With enough data and at different frequencies for the same and different
subjects you should be able to come up with some mappings of what parts of
the process are linear and what are not.

The biggest difficulty I would thing is that like anything in your body if
you don't use it you lose it, so a great deal of the problem could simply
be the atrophy of neurological components. This I would guess lead to
significant changes in how subjects respond over time. It may take a
significant amount od stimulation over time before responses become
consistent and predictable. I would thinks subjects with recent hearing
loss of the type you are working with would be better candidates to start
with to remove that uncertainty.

-jim

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On 2006-12-28, Chetan Vinchhi <vinchhi@gmail.com> wrote:
>
> An approximation to this could be to fill a human skull with silly
> putty

We should ask some of the posters here about their own experiences
having heads filled with silly putty...

-- 
Ben Jackson AD7GD
<ben@ben.com>
http://www.ben.com/