A colleague of mine was unwise enough to use a blue tooth earpiece 
with his cell phone.  All it took was one of those loud telco blasts 
due to a wrong number or some such and he had  significant hearing 
damage in that ear.

Remember that sound falls off as the square of distance.  Combining 
the closeness of an earpiece with the sealing of the ear canal makes 
for very high levels.

On another matter, I am unsure how much the normal roll off of high 
frequencies that comes with age actually effects the ability of an 
audio engineer to do her/his job.  Unless there is a problem with 
noise above 10 KHz, it is more important to be a trained listener. 
It is the lack of listening skills much more often than hearing loss 
that makes for a bad recording or restoration.

Bob Cham



>Hi Stewart:
>
>These hearing tests were discussed a couple of years ago on the 
>Ampex List. Apparently, there is controversy as to how accurate or 
>useful they are. That said, yes I do get my hearing checked every 
>couple of years and yes it's still good according to the test 
>results. In "young middle age," I can't hear above 15-16kHz anymore, 
>but the loss is uniform to both ears. Since at least age 30, I have 
>watched carefully what sort of sound pressure levels I expose myself 
>to. I wish I had worn better earplugs or attended fewer rock 
>concerts as a youngster. Although I am a member of the "Walkman 
>Generation," I never turned to 11, so my ears weren't exposed to 
>prolonged close-up blasts.
>
>The hearing tests got me curious about sound pressure levels in the 
>typical middle class northeastern environment. I found a couple of 
>danger flags:
>
>1. certain electric tools or shop-vacs in a closed garage can 
>produce 100dB spl.
>2. lawn tools, especially powered leaf-blowers, also produce very high spl's.
>3. it's surprising what the underlying noise level is in the typical 
>car on a typically ill-maintained US interstate at cruising speed. 
>Add on top of that enough volume from the speakers for audibility of 
>music or speech and you're doing some ear-assaulting.
>
>For the first two items, I highly recommend earplugs, at all times. 
>For the third, best to not fight road noise too much, some driving 
>situations are just too loud for music listening. Windows open at 
>highway speeds is ear-damaging loud in almost all vehicles.
>
>Also, cellphones can probably do some hearing damage. Apparently, 
>the cell systems don't have to abide by the rules than landlines do 
>about impulse noise levels and variances in volume on the other end 
>of the conversation. Things can go from too soft to too loud very 
>quickly on a cellphone, particularly through an in-ear bluetooth 
>device.
>
>Speaking of phones -- here's a quick tip I learned from my parents. 
>They used to reality-check their hearing by picking up a 
>standard-issue Western Electric telephone and listening to the 
>dialtone. If it sounded the same in both ears, they knew they were 
>good to go. If it was markedly different in one ear, they'd find out 
>why. If it was slightly different in one ear, they'd know to 
>compensate with their brain. How does it get slightly different? 
>Spend an hour talking on the phone before you head into the studio 
>and then see if you hear the same out of both ears (unless you make 
>it a point to frequently switch ears where the phone is pointed). 
>This is one of many reasons I don't like taking phone calls while 
>I'm working with sound.
>
>-- Tom Fine
>
>----- Original Message ----- From: "Stewart Gooderman" <[log in to unmask]>
>To: <[log in to unmask]>
>Sent: Sunday, March 06, 2011 5:18 PM
>Subject: Re: [ARSCLIST] Turnover and rolloff curves for correct 
>playback of 78 rpm records!
>
>>From someone who is not a professional in the field, but loves the 
>>process of sound restoration and recognizes it's importance to 
>>history and who is an optometrist who professionally has his hands 
>>in the human sense of vision rather than the sense of sound:
>>
>>Do sound restorers routinely get their hearing checked to rule out 
>>sensory induced bias?
>>
>>DrG
>>
>>On 3/6/11 4:04 AM, Tom Fine wrote:
>>>One man's opinions/experiences ...
>>>
>>>You need to use your ears.


-- 
Bob Cham
KTRU FM
Houston