Next message: bob england: "T&T: RE RE Noise tolerance"
In a message dated 7/31/04 12:03:50 AM, Bob writes:
<< I have found, from personal experience, that if you spend some time in
very
close proximity to very loud noises you can develope a high tolerance to
that particular frequency. >>
Unfortunately this is due to temporary, and sometimes permanent, ear damage.
Continuous exposure to high level sound of a particular frequency will
macerate the hair cells in the cochlea which respond to that pitch. This phenomenon
was so common with airplane pilots who logged many hours in piston engine
powered aircraft that acousticians had a name for it - "the 4000 cycle notch."
Hearing was relatively normal below that frequency, and not too bad above it, but
showed a drop of up to 30 decibels near the 4000 cps range. Unfortunately much
of the information content of speech is in the 1000 cps to 4000 cps region.
The moral: If you want to hear your grandchildren's first words, quiet your old
Detroits.
Larry Z
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