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Re: Auditory illusions
Hi Nedra,
My short answer would be ... auditory illusions give nothing to
improving and adapting hearing aid design. At the same time I would say
... if you loosely call psychoacoustics 'auditory illusions' then they
give everything to hearing aid design !!!
Here is the long answer ...
Currently we do use psychoacoustics to drive hearing aid algorithms...
here is why ...
You can think of the hearnig aid as starting (in the old days) with the
ear trumpet :
http://www.google.com/search?client=ubuntu&channel=fs&q=ear%20trumpet&oe=utf-8&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&hl=en&tab=wi&biw=1440&bih=884
Then with the advent of electronics, it was replaced by an electrical
amplifier, rather then the analog amplifier. Rather large body worn
electronic units.
Then, these gradually miniaturised ... and frequency channels were added
to the electronics.
Finally we decided that hearing is nonlinear and we should add
nonlinearity to each frequency channel.
This marks our current point in time ... as you can see there is a very
strong link between the ear trumpet and our current hearing aid designs
... the nonlinear sub-band amplifiers.
There are many bells and whistles which we now add to this hearing aid
core ... these mostly include methods to try to reduce noise and to make
wearing the algorithms more comfortable.
Most of the 'hearing correction' is going to come from the core
technology, say of the total hearing improvement and ON AVERAGE, a small
percentage of improvement will come from the bells and whistles. ...
Now the core tends to be a generic WOLA filter...
Consequently one must ask ... how do we construct (prescribe) the core
nonlinear sub-banding ?
The answer is ... that you use psychoacoustics ... and there are
different methods for doing this.
Currently the most popular methods are either :
a] Loudness maximisation
b] Speech intelligibility index maximisation (without exceeding normal
hearing loudness)
It is estimated that about 80% of hearing aids are prescribed using 'b]'.
These two psychoacoustics algorithms are methods for curve matching our
higher illusion of what we call 'loudness' and curve matching which
allows us to match hearing properties to speech intelligibility.
So in that respect, I would imagine that 'auditory illusions' currently
aren't really used to prescribe hearing aids.
However if you loosely call psychoacoustics the art of mapping 'auditory
illusions' down to mathematical descriptions (curves) then they are what
allows us to map how we think (on a very high and convoluded level) the
brain hears and how to prescribe hearing aids.
By the way, this method for producing hearing aids helps a bit, however
it leaves a lot to be desired ... there is no perfect device for the
correction for hearing problems. I certainly am betting that taking a
physiological approach rather then psychoacoustical approach would give
better results ... but that remains to be proven ... clinically.
I guess you already know this however ... being an audiologist ?
Matt
On 29/07/11 05:30, Nedra Floyd-Pautler wrote:
I'm a science writer/audiologist researching an article on auditory illusions. What value do they have "on the ground" for proletariat with hearing deficits? Do what they tells us about the brain and hearing have application to hearing aid design?
Thank you,
Nedra Floyd-Pautler
www.thenedra.com
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