Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!accuvax.nwu.edu!nucsrl!telecom-request
From: hrs1@cbnewsi.ATT.COM (herman.r.silbiger)
Newsgroups: comp.dcom.telecom
Subject: Re: Loud Signal Tones vs. Your Ears
Message-ID: <5380@accuvax.nwu.edu>
Date: 19 Mar 90 20:58:29 GMT
Sender: news@accuvax.nwu.edu
Organization: AT&T Bell Laboratories
Lines: 21
Approved: Telecom@eecs.nwu.edu
X-Submissions-To: telecom@eecs.nwu.edu
X-Administrivia-To: telecom-request@eecs.nwu.edu
X-Telecom-Digest: Volume 10, Issue 186, Message 8 of 9


In article <5318@accuvax.nwu.edu>, 0002909785@mcimail.com (J. Stephen Reed) 
writes:

> Apparently these tones are about 116 decibels.  This level plays havoc
> with anyone with sensitive hearing, and especially with those who have
> hearing impairments and use amplifiers on the line.  Amplification can
> put these tones up in the range of a jet engine at 100 feet away.

I don't know who measured the level of these tones, or how they were
measured, but I doubt very much that the level of those tones is 116
dB.  However, even if they were at that level, they could not cause
any hearing damage at those short durations.  In addition all
telephone receivers made by reputable manufacturers have a limiting
device installed across the receiver capsule terminals (a varistor),
which limits at 119 dB re 20 microPascals, so that regardless of any
amplification on the line, harmful levels are not possible when
hearing loud tones or noises for short periods.

Herman Silbiger