Re: Adjusting Aid to Match Audiogram Curves

"Mason C" <masonc2XXX@XXXearthlink.net> wrote in message
news:o0kus3l92q2v5pqfot2e32p7ljev3h3m8q@4ax.com...
>I noticed somewhere here (lost it) someone disappointed that the
> adjustment of their aid did not match their audiogram.
>
> In my days of repairing vacuum-tube aids we did try to match
> the frequency response of the aid to compensate the loss.
> This can be done much more precisely with modern aids.
>
> BUT !    Is strict frequency compensation the best way to adjust
> an aid?  My impression is NO.  My impression is that it's much
> more complicated and requires either expertise or intelligent
> self-adjustment.  What you hear is what matters, not the curves.
>
> Can experts here comment on this, Michael and all?
>
>     MasonC
>

Your intuition is correct. Harvard tried frequency matching 60 years ago,
exactly as you describe it here, with vacuum tubes (it wasn't you, was it?)
The fidelity of their test instrument equaled or surpassed today's
instruments, but were huge, on the order of a large cardboard box. Hardly
fittable in the ear. Their experiments showed that frequency matching does
not equal hearing matching because of the non-linear, bionic makeup of the
cochlea. Since then hundreds of schemes have been posited to find a simple
way to produce near normal hearing. One that I learned 35 years ago was the
half gain rule. So much for that.

We're still trying to find the magic formula.

The problem I see with self programming is that some people can, by
experimentation, find a setting which meets their minimal needs. This is not
to be confused with the scientific, analytical approach, required of me by
law. Many other people, who cannot find this minimal level of adequacy,
become convinced they cannot wear hearing aids and quit trying, not
believing anyone who tries to help. They cry, "cheat", "crook",
"thief",
when all we audiologists are trying to do is help.

The science is, at this point, just guesswork. Manufacturers use their own
formulae, calling them "easy fit" or some other reassuring phraseology,
when, in fact, nobody has the answer yet. What gives the audiologist the
advantage is that we have already tried many of the various schemes and have
tried them on many different people with different hearing losses. This
experience does give a great advantage, imho, over the individual who is
self fitting by random experimentation.
But it ain't perfect and we can only give an educated guess most of the
time.
Beware of anyone who has all the answers.

MR
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