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Decibel

Decibels (dB) are units of measurement for the intensity of a sound. Sound intensity is the energy that a sound wave carries and that determines its amplitude. Amplitude is the pressure that air particles exert on each other as they are momentarily squashed together. Intensity and amplitude are the physical correlates of loudness, although their relationship to loudness is nonlinear.

The Decibel Scale

The decibel scale is relative and logarithmic to the base 10. It expresses how much greater or lesser the intensity of one sound is relative to another. Often in speech acoustics it is unimportant to know the absolute intensity of a sound but important to know the relative intensity—for example, when comparing sounds from different classes or two formants, or harmonics of the ...

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