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In article <154@aiva.ed.ac.uk>, jeff@aiva.ed.ac.uk (Jeff Dalton) writes:
> >It seems that a middle-aged woman who had worked as a switchboard
> >operator for 20-some years had applied for compensation resulting from
> >partial hearing loss in one ear.  Her allegation was that then presence
> >of clicks and loud noises in her "headset ear" over many years caused 
> 
> Could the "many years" have been significant?  My understanding was that
> prolonged exposure to noise levels well below the threshold of pain (say
> at 90 db) could cause hearing loss through damage to the inner ear.  The
> maximum level of transmitted sound would not be the only factor.

	You could very well be correct.  My involvement in this matter
happened in 1975.  Since that time, however, a number of occupational
health studies of hearing loss have occurred (spurred by OSHA, of course).
	I should have posted a bit more information about the case.
The woman had a hearing loss in _both_ ears, although she only wore a
headset in one ear.  The headset ear had a greater hearing loss than
the non-headset ear.
	Two otolaryngologists diagnosed the woman as having a hearing
disorder known as otosclerosis; this condition is an organic disease,
and is not the result of any excessive sound level exposure.  However,
the woman wanted to get workmen's compensation benefits (I suppose you
can't blame her for trying :-) ), so she claimed that the greater
hearing loss in her headset ear was NOT otosclerosis, but was an
occupational injury.
	All I did was to examine the electronics and acoustics of the
headset and telephone switchboard environment, and give the acoustic
measurement data (sound pressure level, etc.) to an otolaryngologist
for use in his medical evaluation.
	The woman was denied workmen's compensation benefits because:
(1) she had a clearly diagnosed organic ear disease which was not
related to occupational exposure; and (2) based upon the measurements
of acoustic exposure and the generally accepted standards of the time,
the sound pressure exposure was insufficient to cause hearing loss.
	The truth (with some hindsight): Who knows?

<>  Larry Lippman @ Recognition Research Corp., Clarence, New York
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