A Decibel (dB) is a unit of measurement of the sound intensity and other physical quantities that is usually measured with microphones and respond (approximately) proportionally to the sound pressure, p.
Reference Definition by Greenfacts.org: The decibel (dB) is a unit used to measure sound intensity and other physical quantities. A decibel is one tenth of a bel (B), a unit named after Graham Bell, the inventor of the telephone. Its logarithmic scale is convenient to represent the entire range of human hearing. The smallest audible sound to humans is typically 0 dB SPL (hearing threshold). Because the decibel scale is logarithmic, a three-decibel increase in sound level already represents a doubling of [sound] intensity. For example, a normal conversation may be about 65 dB and someone shouting can typically be around 80dB. The difference is only 15 dB but the shouting is 30 times as intensive.
Related Definitions in the Project: The Property and Unit
