Sound measurements | |
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Characteristic
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Symbols
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Sound pressure | p, SPL |
Particle velocity | v, SVL |
Particle displacement | δ |
Sound intensity | I, SIL |
Sound power | P, SWL |
Sound energy | W |
Sound energy density | w |
Sound exposure | E, SEL |
Acoustic impedance | Z |
Speed of sound | c |
Audio frequency | AF |
Transmission loss | TL |
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Sound energy is a form of energy associated with the vibration of matter. The SI unit of sound energy is the joule (J). Sound is a mechanical wave and as such consists physically in oscillatory elastic compression and in oscillatory displacement of a fluid. Therefore, the medium acts as storage for both potential and kinetic energy as well.
Consequently, the sound energy in a volume of interest is defined as the sum of the potential and kinetic energy densities integrated over that volume:
where