decibel (dB)

Unit of measurement of the loudness (intensity) of a sound or the strength of a signal, computed as the signal to noise ratio. Loudness of normal adult human voice is about 70 db at three feet. According to common workplace safety standards (such as those prescribed by OSHA), workers may not be exposed to sound louder than 90 db (as an average) over an eight hour period. One decibel is one-tenth (deci) of 'bel,' a rarely used unit of loudness named in honor of the US inventor of telephone, Alexander Graham Bell (1847-1922). Since the decibel scale is a logarithmic scale, it increases/decreases by a factor of 10 from one scale increment to the next adjacent one.