psychoacoustics

[pk@mainstring.win.net (Pat Kirtley)]

David Myers <dmgraph@bway.net> wrote:

>Now this is really getting off topic I guess, but with all the talk here
>about ears & perception of sound I'd like to ask the following of you
>intelligent people:
>
>do you hear a sound in your head?
>
>I've gotten some very interesting answers to this question, usually from
>musicians and artists.  To be clear, I don't mean tinnitus or any similar
>malady.  I believe that John Cage called it the sound of the nervous 
>system
>working.  Different people's perception/non-perception of the phenomenon 
>is
>quite varied and curious.
>

About 5 years or so ago I heard a discussion (on NPR) of the findings of
some researchers that was highly interesting. In studying victims of
tinnitus they found that some sufferers with acute cases of the affliction
actually had sounds coming out of their ears! The high-pitched tone was
somehow being produced within the ear, and excited the eardrum in such a
way as to broadcast it externally. 

The appearance of the phenomenon led them to further studies and yielded a
hypothesis: The ringing is a real, physical attribute of the hearing
process, and in normally functioning people it functions as an "active
feedback" mechanism to allow the ear to hear extremely weak sounds. In
other words, some physical mechanism inside the ear is able to oscillate in
pure tones at frequencies in the range of desired sounds. Tinnitus occurs
when this process goes wild for various reasons (ear damage due to loud
noises, disease, infection etc.). In individuals with normal hearing, the
tone is very weak and hardly ever perceived consciously.

I never heard any more about the research, and never was able to locate any
materials. I thought it was fascinating, (i.e. the ear as an "actively
resonant" device) and a plausible theory about how our ears are so
sensitive to extremely weak sound intensities. 

PK