"Christian McArdle" wrote in message
t...
Why give it a name then if it is purely abstract?

Because it is a very useful concept and deserves a name. What would you
call
a decibel then? The unit formerly known as decibel? TUFKAD. Catchy. There
are other dimensionless units you would have to expunge, of course.
Percent
(%) is a useful one that would have to go.

FWIW, my dictionary says it's a unit for measuring sound.

Your dictionary is wrong. It is used to measure power ratios (usually in
oscillatory systems of large dynamic range). Sound power is only one of
the
measurements it is useful for. Amongst other things, it is also used to
measure vibrations and to compare electronic signals, not necessarily
audio
in frequency or nature.

Christian.
BEng (Electronic and Electrical Engineering)


Everybody's right!

Main Entry: deci·bel
Pronunciation: 'de-s&-"bel, -b&l
Function: noun
Etymology: International Scientific Vocabulary deci- + bel
Date: 1928
1 a : a unit for expressing the ratio of two amounts of electric or acoustic
signal power equal to 10 times the common logarithm of this ratio b : a unit
for expressing the ratio of the magnitudes of two electric voltages or
currents or analogous acoustic quantities equal to 20 times the common
logarithm of the voltage or current ratio
2 : a unit for expressing the relative intensity of sounds on a scale from
zero for the average least perceptible sound to about 130 for the average
pain level
3 : degree of loudness; also : extremely loud sound -- usually used in
plural
www.webster.com