Definition: Unit expressing the relative intensity of a sound. The intensity in bels is the logarithm (to the base 10) of the ratio of the power of the sound to that of a reference sound. Ordinarily, the reference sound is assumed to be one with a power of 10−16 watts per sq cm, approximately the threshold of a normal human ear at 1000 Hz.
[A.G. Bell, Scottish-U.S. scientist, 1847–1922]
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Examples: glitazone, GI cocktail, etc.