[OT] Decibels and the ear [was: Re: [plug] Hot and bothered CPU hankers for cool breeze]

[Bernd Felsche]

On Wed, Dec 17, 2003 at 05:55:30PM +0800, bern wrote:

> On Wed, 2003-12-17 at 10:56, James Devenish wrote:

> > Heh, I used to wear earplugs when I was in a very quiet office.
> > Maybe I should do the same where I am now, as I continually have
> > nefarious thoughts about disabling the machine that's next to
> > mine.

> Not wishing to stir the pot but anything less than 85db is
> supposed to be not damaging to the hearing

According to who?

Damage to hearing not only depends on peak noise levels, but also
the length of exposure to noise as well as the individual's health
and age. (Ref Brüel & Kjær "Acoustic Noise Measurements", 1979).

24hrs at 80dBA *may* be as damaging as 85 dBA for 8 hours and less
than 65 dBA for 16 hours. ISO standards generally disregard noises
of less than 80 dBA in assessing the daily noise dose; but that
doesn't say that 80 dBA is _safe_.

But it depends on the individual; the older you get, the less likely
you are to "recover" from doses of loud noise. One of the important
thing is that the ears have quiet period in which to recover; all
those folicles need lubricating and moisturising. If it doesn't
happen, then there's permanent hearing loss.

Determining what's a safe noise level is practically impossible to
determine. Hearing loss due to age is largely indiscernable from
hearing loss due to mild noise exposure. Hence no absolutes.

-- 
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