The energy in sound waves.

kinetic energy/unit volume: tex2html_wrap127 .

The potential energy in compressed gas is an average of 0, to first order. To second order it is tex2html_wrap128 . so the kinetic and potential energy terms are the same.

Energy is propagated at the group velocity, tex2html_wrap129 . Energy flux = tex2html_wrap130 where Z is the acoustic impedance.

microphones detect pressure variation rather than power variation.

The pressure fluctation is tex2html_wrap131 where P is the power.

A decibal is tex2html_wrap132 .

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