de·ci·bel 
(dĕsə-bəl, -bĕl′)
(dĕsə-bəl, -bĕl′)n. Abbr. dB
A unit used to express relative difference in power or intensity, usually between two acoustic or electric signals, equal to ten times the common logarithm of the ratio of the two levels.
[DECI- + BEL.]
decibelrange of human hearing in decibels