What is the reference value used for pressure in decibel calculations?

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What is the reference value used for pressure in decibel calculations?

In decibel calculations for sound pressure level, a fixed reference pressure is needed so that the scale has a meaningful zero point. In air, the reference pressure is 20 microPascals, which is 2×10^-5 pascals. The SPL is defined as 20 log10(p/p0), where p is the measured sound pressure and p0 is this reference value. This choice makes the quietest perceptible sound by a typical ear correspond to 0 dB, and it provides a convenient, proportional scale: ten times the reference pressure gives about 20 dB, a hundred times gives about 40 dB, and so on. So the standard reference pressure used in decibel calculations is 20 μPa (0.00002 Pa).

In decibel calculations for sound pressure level, a fixed reference pressure is needed so that the scale has a meaningful zero point. In air, the reference pressure is 20 microPascals, which is 2×10^-5 pascals. The SPL is defined as 20 log10(p/p0), where p is the measured sound pressure and p0 is this reference value. This choice makes the quietest perceptible sound by a typical ear correspond to 0 dB, and it provides a convenient, proportional scale: ten times the reference pressure gives about 20 dB, a hundred times gives about 40 dB, and so on. So the standard reference pressure used in decibel calculations is 20 μPa (0.00002 Pa).

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