The length of time it takes to
sustain hearing damage drops off
rapidly the louder the sound is.
The loudest sounds can cause
damage in an instant.
However, even a seemingly
painless, tolerable level can be
damaging after say 8 hours of
exposure. Your local OHS
authority no doubt
has the tables.
What I propose here is a system of
two devices.
1. The Decibel Dosimeter.
A tiny dB meter and data logger on
a chip, which can be worn either
behind the ear or as a natty
ear-ring. It logs dB level against
time exposed.
2. Exposure limiting headphones.
These would be integrated
ambient noise cancellation 'phones
and stereo 'phones you can plug
into your walkperson/iDevice. An
embedded CPU in the earmuff
reads the dB exposure log from the
'meter.
As the exposure approaches
damaging amounts, the 'phones
crank down a limiter which keeps
your personal stereo at a safe
level, accounting for what you've
already been exposed to.
So if you've already been exposed
to 8 hours in a foundry, you won't
be able to destroy your hearing
(further) by cranking Def Leppard
(Def Jam/Def Penalty Kru) on the
bus home.
Having the logger separate from
the 'phones allows it to log
exposure from any source,
including that played through the
'phones.