Sound exposure

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Sound measurements
Characteristic
Symbol
 Sound pressure  p · SPL
 Particle velocity  v · SVL
 Particle displacement  ξ
 Sound intensity  I · SIL
 Sound power  P · SWL
 Sound energy  W
 Sound energy density  w
 Sound exposure  E · SEL
 Sound energy flux  Q
 Acoustic impedance  Z
 Speed of sound  c
 Audio frequency  AF

Sound exposure is the time average of squared sound pressure.

Mathematical definition[edit]

Sound exposure during time T, denoted E and measured in Pa2·s, is given by:

E = \frac{1}{T}\int_0^T p(t)^2\, \mathrm{d}t

where:

  • T is the time, measured in s;
  • p is the sound pressure, measured in Pa.

Sound exposure level[edit]

For other uses, see Sound level.

Sound exposure level (SEL) or acoustic exposure level is a logarithmic measure of sound exposure in comparison to a reference value.
Sound exposure level, denoted LE and measured in dB, is given by:

L_E = 10 \log_{10}\left(\frac{E}{E_0}\right)~\text{dB}

where:

  • E is the sound exposure, measured in Pa2·s;
  • E0 is the reference sound exposure, measured in Pa2·s.

The reference sound exposure is 400 μPa2·s for sound in air and 1 μPa2·s for sound in water.