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Presbyacusis

Richard Bishop richard at ovation.wgtn.planet.co.nz
Wed Oct 9 08:51:20 EST 1996


I would very much like to have your comments on the issue of 
presbyacusis, or age-related hearing loss.   There is a common 
perception that older people have poorer hearing, and I don't 
think that this is disputed.   However, I question the common 
interpretation placed on this observation which is that age 
causes hearing loss.   In other words, the attribution of 
cause to a correlation.

I am concerned about this for a number of reasons.   One is 
that various 3rd party payment schemes utilise an age-related 
"correction" which reduces the amount of financial assistance 
available to a person with hearing impairment on the basis of 
the degree of hearing loss "expected" for someone of that age. 
  This may make some compensation schemes unavailable to 
elderly people who suffer hearing loss from compensatable 
causes.

Another reason for my concern is that expectations of elderly 
peoples' hearing performance is lower because of this.   So if 
I am an old man and I tell my family doctor that I am having 
trouble hearing properly, I am likely to be told that I must 
expect this because I am old.   This may have been a workable 
strategy when old people had the grace to decently keep 
themselves to themselves but these days the expectancy of 
greater quality of life means that elderly people often expect 
to be able to continue with their preferred social activities 
indefinitely, and these can suffer significantly if the 
person's hearing is poor, of course.

My perception of this issue is that age-related hearing loss 
is often presented (perhaps in an unspoken way) as some sort 
of steady progression of hearing loss (as measured by pure 
tone audiometry), with the implication that serial audiometry 
over the years will expose this insidious process.

My clinical experience, however, over a good number of years 
(15 in my present town) is the opposite.   I find that 
peoples' hearing levels tend to remain stable over the years 
in the great majority of cases.   Where there is a 
deterioration, it can usually be sttributable to either:
	1	Accident - noise exposure, head/ear/neck 
injury, iatrogenic factors, etc;
	2	Disease - viral agents, middle ear disease, 
hydrops, etc; or
	3	Hereditary factors - where there is a positive 
history of familial hearing loss, often with age-specific 
onset.

My interpretation of these observations is that, if you can 
avoid these 3 causative factors (the 3 horsemen) then you can 
reasonably expect your hearing to remain good throughout your 
lifetime. However, because the cochlea is a very vulnerable 
organ, accumulated insults throughout your life can contribute 
to poorer hearing in latter years;   in other words, it is 
very difficult to dodge these factors, but not impossible to 
do so.   

I would prefer to see a definition of presbyacusis to be 
"idiopathic hearing loss sometimes observed in the elderly".

I would be very grateful for your thoughts on this matter to 
try to clear up my thinking on it if I have made a fundamental 
error.   I would also be interested in whether you know of any 
elderly people with good hearing!

Thanks for your time,
--
Richard Bishop
Audiologist
Wellington
New Zealand



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