Klarinet Archive - Posting 000352.txt from 2001/05

From: Richard Bush <rbushidioglot@-----.com>
Subj: Re: [kl] ...more about sensitivity & decibels
Date: Sun, 13 May 2001 02:13:15 -0400

Dear Bill,

You need to quit talking to us about this and go to the school board. If
your concern falls on deaf ears, call on OSHA. If that doesn't work go to a
lawyer and have him talk to the school board. If litigation is the only
recourse, and if you have the means, go for it. I would also make the DJ
enterprise supplying these very loud sounds party to such a law suit.

Your complaints are real. Your concern is real and I don't doubt at all your
characterization of the volume or the measurements read on your decibel
meter.

William Wright wrote:

> Despite the one-liner about my daighetr cleaning her room, I wasn't
> jesting that she has hypersensitive hearing, nor about "turning nerves
> off". She has been tested by audiologists and counselled on how to
> cope, etc.
>
> Therefore last night was astonishing to me, and it also made me
> angry:
>
> I haven't chaperoned (or attended) a teen-age dance for 20-30 years
> now. I had no idea what occurs nowadays when a "DJ" plays canned music
> at these things. The barrage of sound was so fierce that I was unable
> to remain inside the building and carry out my chaperone duties.
> Mercifully they shifted me to 'outdoors sentry' instead.
>
> I knew that my daughter couldn't handle that much noise, and so I
> suggested that I take her home and then I would return to perform my
> sentry duty. To my absolute astonishment, she told me, "No problem,
> this isn't loud."
>
> If ever there was an example of how a musician might 'feel' tone
> through a clarinet's holes (see below about misinterpreting bone
> conduction) and yet not feel excruciating pain while doing household
> chores, this was certainly it. Somehow my daughter managed to "turn
> off" an entire neural pathway.
>
> Why was I angry? Because after a couple of minutes, I 'woke up'
> and realized the potential for hearing damage to my daughter and to all
> the other children. I was not alone in this. Several other adults
> had the same complaint, and the teachers agreed and they forced the DJ
> to turn the volume down a bit.
> But afterwards, I was *still* unable to remain in the building for
> more than 30 seconds or so. At this point, other adults were shrugging
> their shoulders and saying "It's OK now, the kids think it's cool."
>
> I happen to have a decibel meter with a few extra functions
> (A-scale, C-scale, adjustable sample period, peak vs. weighted average,
> etc). So I went home and got it. The gentlest 'song' that I tested
> was 102 dbA. The loudest song was 109 dbA. These readings were in
> the dance area, not standing directly in front of one of the large
> speakers. The lowest reading that I could obtain was 92 dbA if I stood
> in the doorway that was the main entrance to the building (cafeteria,
> actually).
> My meter is not a laboratory instrument, but on one occasion I used
> it side-by-side with a professionally calibrated meter in the
> $10,000-$20,000 range operated by a certified technician. The readings
> were similar enough for estimating dbA levels.
>
> I'm not a physician, but most audiologists say that the risk of
> permanent hearing damage begins at 85 dbA of repeated extended
> exposures. A web page from NIH (National Institute of Health) talks
> about risk of permanent hearing damage after 60 seconds of exposure to
> 110 dbA or after 15 minutes at 100 dbA.
>
> ....and these readings were taken _AFTER_ the DJ turned it down
> enough that I and other adults could notice a reduction.
>
> A few months ago, this list discussed orchestra members wearing
> earplugs. I should search the archives to see if any of those posts
> mention specific decibel readings.
>
> The question of what I'm going to do about this incident isn't
> relevant to the Klarinet list's conversation, but it does provide an
> excellent real-life example of how much ability the human nervous system
> has to turn its perceptions "on" or "off" --- although I don't know
> enough physiology to know how sensitive a fingertip is under laboratory
> conditions, nor whether a musician may report feeling tone via the
> fingers even though the sensation actually arrived through bone
> conduction in the head area.
>
> ......and also BTW, my ears were still ringing and my hearing was
> still noticeably (to my perception) duller than normal when I practiced
> 10 hours later. It's been 22 hours now, and most of the effect appears
> to have disappeared..... I hope..... it's all very subjective.
>
> Cheers,
> Bill
>
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