decibel

(noun)

A common measure of sound intensity that is one tenth of a bel on the logarithmic intensity scale. It is defined as dB = 10 * log10(P 1/P 2), where P1 and P2 are the relative powers of the sound.

Related Terms

Examples of decibel in the following topics:

  • Decibels

    • The decibel is a logarithmic unit used to quantify sound levels, by comparing a physical quantity to a reference level.
    • The decibel, dB, is commonly used to quantify sound levels, although it is not a unit of sound, but a unit of pressure.
    • The decibel is a logarithmic unit that indicates the ratio if a physical quantity to a reference level.
    • Although the decibel can be used to talk about a number of different subjects, in this atom we are going to cover its use in acoustics and sound level.
    • Loudness is a measure of sound intensity taking frequency into account, and is called a A-weighted decibel, dB(A), or a phon.

  • Intensity

    • Use the following information to calculate (1) the sound intensity and (2) the decibel level. p = 0.656 Pavw= 331 m/s2, at 0 degrees Celsius.
    • Now we want to convert this intensity into decibel level:$\beta = 10 log_{10}\frac {5.04*10^{-4}}{1*10^(-12)}\\ \beta = 10 log_{10}5.04*10^8\\ \beta = 10*8.70dB\\ \beta = 87dB$
    • Although the units for sound intensity are technically watts per meter squared, it is much more common for it to be referred to as decibels, dB.
    • A decibel is a ratio of the observed amplitude, or intensity level to a reference, which is 0 dB.
    • The equation for this is:$\beta = 10 log_{10}\frac I{I_0}$β - decibel levelI - Observed intensityI0- Reference intensity.For more on decibels, please refer to the Decibel Atom.