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.

  • Wave Amplitude and Loudness

    • Scientists measure the amplitude of sound waves in decibels.
    • Leaves rustling in the wind are about 10 decibels; a jet engine is about 120 decibels.
    • Dynamic levels don't correspond to a measured decibel level.

  • Sound

    • For sound, volume is measured in decibels (dB).
    • Humans speak normally at 60 decibels.

  • Dynamics and Accents

    • The amplitude of a sound is a particular number, usually measured in decibels, but dynamics are relative; an orchestra playing fortissimo sounds much louder than a single violin playing fortissimo.

  • Graphing on Computers and Calculators

    • Many graphing calculators can be attached to devices like electronic thermometers, pH gauges, weather instruments, decibel and light meters, accelerometers, and other sensors and therefore function as data loggers, as well as WiFi or other communication modules for monitoring, polling and interaction with the teacher.

  • Volume

    • Loudness is then a subjective measure of the listener, which is often confused with objective measures of sound strength such as sound pressure level (in decibels), sound intensity, or sound power.

  • Common Bases of Logarithms

    • For example, the decibel is a unit quantifying signal power log-ratios and amplitude log-ratios (of which sound pressure is a common example).