What is a Decibel?
A decibel is one unit on the decibel scale, which is a logarithmic scale. The name means one-tenth of a bel, a bel being an eponymous unit named for Alexander Graham Bell and used to compare power in electrical communication, voltage, or intensity of sound. The abbreviation of bel is B and decibel, dB. 10 dB = 1 B The primary use of the decibel scale today is to test audibility, and the results are called the sound-pressure level (SPL), which is similar to loudness. The Occupational Safety and Health Association (OSHA) has set guidelines to help people determine the maximum loudness they should be exposed to. The SPL level that OSHA recommends is 85 decibels, above which special ear protection is required. Eighty-five decibels is the threshold for the possibility of noise-related hearing loss, and this guideline is intended to prevent such hearing loss. This figure suggests that many people who do not currently use ear protection should consider it. The following chart reveals that a g
Joe Wolfe / J.Wolfe@unsw.edu.au. And what are the different types of decibel measurement: dB, dBA, dBC, dBV, dBm and dBi? How are they related to loudness? (A related page allows you to measure your hearing response and to compare with standard hearing curves.) Plot of 10 log (P2/P1) Definition and examples The decibel (dB) is used to measure sound level, but it is also widely used in electronics, signals and communication. The dB is a logarithmic unit used to describe a ratio. The ratio may be power, sound pressure, voltage or intensity or several other things. Later on we relate dB to the phon and the sone (other units related to loudness). But first, to get a taste for logarithmic units, let’s look at some numbers. (If you have forgotten, go to What is a logarithm?) For instance, suppose we have two loudspeakers, the first playing a sound with power P1, and another playing a louder version of the same sound with power P2, but everything else (how far away, frequency) kept the same.
