> Loss of hearing with age at both ends of the spectrum is perfectly
> common. But I don't know whether loss in the range of 80-100 Hz is
> within what would be considered normal and particularly for your age.
> I'll bet that the Silver Schnozz knows the answer.
>
I'm glad you asked. ;)
Actually, I do have some thoughts on this one.
Hearing loss in the range of 80-100 Hz is uncommon unless it's from a
continuous tone or drone. The cilia in the cochlea resonate at certain
frequencies. When confronted by exposure to a specific tone over a period of
time or at high volume level the cilia which are at the resonate points will
break off and a notch in the hearing will occur at that frequency. Most
violinists have severe hearing loss in one ear from tuning the instrument.
In western Iowa, the interstate is grooved in a way that the tires whine
very loudly--when traveling that direction I wear earplugs to protect my
hearing.
Unfortunately, many small propeller airplanes are a major problem because
RPMs are usually pretty defined for climb and cruise settings. An additional
problem is the aluminum skin used for most small airplanes vibrates like a
drum. There are three ways to address this, though: Thicker aluminum skin,
size and shape of the segments between braces and bonding different
thickness of aluminum or a secondary material to the skin. Sometimes, all
three are used. Oh, another problem is with prop planes with full rounded
canopies which reflect the sound inward to the location of the pilot's head.
These sport/stunt planes absolutely require hearing protection.
The biggest problem with these lower frequencies sounds (also as experienced
at rock concerts and pentecostal church services) is the failure of
ear-canal attenuation to prevent hearing loss and discomfort. Earplugs are
pretty much ineffective for frequencies this low, but will protect hearing
loss of the broader range of frequencies typically experienced in airplanes.
Fully sealing ear muffs (the bigger the better) are your best option, but
much of these lower frequencies (100Hz and down) are conducted to the
cochlea through the jaw bone. This is why construction workers will
experience hearing loss in spite of combined use of earplugs and ear muffs.
But not all is for loss... (pun intended)
I've used and recommend the Bose Aviation Headsets. These aren't the
lower-cost pretty ones which you see fellow airline passengers wearing with
their iPods plugged in, but these are the expensive fully isolating ones
intended for pilots wearing them for many hours a day. Why the Bose Aviation
Headset (X is the current model) is so good is that it compensates for the
jawbone conduction by actually boosting the low frequencies instead of just
nulling them.
These headsets are very expensive (Around USD 900) but if you are a
professional pilot, I'd not be caught anywhere near a prop plane without
them.
As a small child I had two ear infections which left substantial scar tissue
on my eardrums. Basically, since age three, I've had a 30-40% hearing loss,
but what is unusual is with the exception of two minor notches, has not
affected my high-frequency hearing. About six months ago I tested myself
again and I'm still able to hear just over 21 kHz but at much more boost
than five years ago. Oh, one other thing unusual about my hearing is my
much lower threshold of pain. When mixing live concerts/events I adjust
levels so I can not only hear it myself, but I make sure I don't hurt my own
ears. As a result, nearly everybody in the audience is happy. If I'm happy,
they're going to be happy. But on rare occasion I've had to mix LOUD
concerts and I end up mixing using earplugs. I don't go to any concert
without my earplugs no matter what. One time I failed to do so and regretted
it. I didn't know that Doc Severenson in concert was one of the loudest
ever.
AG Ears
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