0002909785@mcimail.com (J. Stephen Reed) (03/19/90)
An article in the [Chicago Tribune], Friday, March 16, noted an
investigation by relevant Illinois state agencies into the three-tone
pattern that is used to precede telco messages. It noted that this
tone pattern is used hundreds of thousands of times per day; in the
Chicago area, on the first day of the mandatory cutover to the 708
suburban area code, it was used 1.6 million times.
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.
The article quoted a Bellcore spokesman to the effect that these tones
were implemented a decade ago -- in pattern, tone, and loudness --
under an international agreement to make them standard worldwide, and
that the loudness is necessary for some automated equipment to catch
the existence of a telco message. The spokesman didn't promise early
changes but said that possible changes would be investigated.
Would anyone here from Bellcore care to amplify :-) on this for us?
And what kind of equipment (for business, I presume) would make use of
these tones? I know I have been bothered by them, and my hearing is
far from bein weak or particularly sensitive.
* * *
Steve Reed -- Liberty Network, Ltd. -- P.O. Box 11296, Chicago, IL 60611
MCI Mail: 290-9785 (0002909785@mcimail.com)
CompuServe: 74766,347 (74766.347@compuserve.com)
"I do not believe in democracy, but I am perfectly willing to admit that it
provides the only really amusing form of government ever endured by mankind."
-- H.L. Mencken
* * *hrs1@cbnewsi.ATT.COM (herman.r.silbiger) (03/20/90)
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