decibel (dB) /des″əbəl/ [L, decimus, one tenth, bel, Alexander G. Bell, Canadian inventor, 1847–1922] , a unit of measure of the intensity of sound. A decibel is one tenth of 1 bel (B); an increase of 1 B is perceived as a 10-fold increase in loudness, based on a sound-pressure reference level of 0.0002 dyne/cm2, or 20 micropascals.
