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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 :

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 ?


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

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