Term: Decibel (dB)

Unit of measurement that compares two values with a ratio. In audio signals, for example, doubling the signal’s voltage (amplitude) represents a 6 dB increase in level. For power (amplification) a 6 dB increase equals a fourfold increase in power. For dB SPL, 0 dB SPL is the threshold of human hearing (for midrange frequencies) and 120 dB SPL is the threshold of pain.