Talk:Bel

The part until the next line has been moved over from Talk:Decibel: Earlier I thought Alexander Graham Bell coined the term "bel" as a measurement of sound and that it was later determined to be so coarse that 1/10th of it proved more useful (the decibel). On seeing someone on this page claim that Bell coined the phrase "decibel" I looked up its history in the Oxford English Dictionary. The OED has their earliest recorded uses in 1928 and 1929; Bell died in 1922.

• the earliest few quotations the OED has on file for "decibel": "1928 Electrical Communication VII. I. 33/2 If common logarithms are used, the reproduction is obtained in Decibels. 1929 W. H. MARTIN in Bell System Techn. Jrnl. VIII. 2 The Bell System has adopted the name ?decibel? for the ?transmission unit?, based on a power ratio of 10·1... For convenience, the symbol ?db? will be employed to indicate the name ?decibel?. 1930 Discovery Dec. 398/2 The band-pass filter, which follows the low frequency modulator, allows the lower side-band to pass with an attenuation of six decibels."
• the earliest few quotations the OED has on file for "bel": "1929 W. H. MARTIN in Bell System Techn. Jrnl. VIII. 2 It was further suggested that the naperian unit be called the ?neper? and that the fundamental decimal unit be called the ?bel?, these names being derived from..Napier..and Alexander Graham Bell. 1930 Gloss. Terms Electr. Engin. (B.S.I.) 13 The bel is a unit used in the comparison of the magnitudes of power, voltages or currents at two different points in a network of lines or apparatus."

Clearly the term "bel" was in use before the term for 1/10th of it came about. Yet it seems odd to me that the terms did not see print for almost a decade. Anyone? Specifically, I'd like to know who made the suggestion for the terms "napier" and "bel." I suspect it wasn't Alexander Graham Bell. --Koyaanis Qatsi

I've generalised the article a bit, since decibels are not just used for acoustics (e.g. they're used to measure the gain of amplifiers and loss of transmission lines.) -- DrBob

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How likely is it, if I find a claim that a sound is at, say, 120dB, that the reference level is indeed 20 micropascals? Similarly, if author A claims that one sound is so many dB, and author B claims that one sound is so many dB, how safe is it to compare the measures given, if neither indicates the reference level? --Ryguasu 04:38 Feb 26, 2003 (UTC)

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This 0 (zero), decibel level also corresponds to one billionth of a watt, 0.000 000 000 001 watt, roughly a mosquito flying 10 feet away.

Watt would be total power, not related to distance; also http://ccms.ntu.edu.tw/~karchung/decibels/decibels1.ppt says 40 dB. - Patrick 09:52 Apr 16, 2003 (UTC)