Re: Selective numbing

["Regis Rossi A. Faria" <regis@xxxxxxxxxx>]

Eliot Handelman wrote:
>
> Andy, during and after exposure to high-intensity high sounds
> my frequency response was noticably numbed. My own voice souded
> different to me afterwards, as though my hearing had been selectively anesthetized,
> though after a few minutes things returned to
> normal. I wonder whether anyone here knows of relevant studies
> involving selected numbing of this sort?

Although I don't have knowledge of formal studies on this (neither
articles) maybe I can add some more flavour to the discussion presenting
an effect I've been experiencing when exposed for some minutes to
"buzzing" noises due to poor shielded microphones cables (bad ground or
bad shield).

After hearing this kind of noise for over 5 minutes (not loud, close in
intensity to a normal human conversation) and turned off the mic (so
stopping the noise) I noticed that all human voices I heard for some
time were kind of "flangered", even my voice sounded as if flanger
effect were being applied. It seems the noise had biased the hearing
hardware so that incoming voice were just analysed with a different bias
and producing a flanger effect. I didn't analyse the noise signal, but I
suspect it is probably very rich in 60Hz (the AC power supply
frequency).

I go to Rock concerts every so often, and sometimes to night clubs with
terrible agressive bass sounds and painful tweeters, and I have never
noticed a flanger effect after exposure to these acoustic poluted
environments. The effect was new to me.

Concerning protective adaptations, I am sure that fine, constant and
"well behaved" buzz that we hear after a rock concert or noisy night
clubs is a result from a protective procedure the hearing hardware uses,
that takes place even at the middle ear (the little bones change their
impedance when loud sounds are present) and/or at the cochlear membrane
and hair cells (which would change how some frequency bands are analysed
or masked).

Regis

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