Sound exposure is the integral, over time, of squared sound pressure. The SI unit of sound exposure is the pascal squared second (Pa<sup>2</sup>÷s).
Sound exposure, denoted E, is defined by
where
Sound exposure level (SEL) is a logarithmic measure of the sound exposure of a sound relative to a reference value.<br> Sound exposure level, denoted L<sub>E</sub> and measured in dB, is defined by
where
The commonly used reference sound exposure in air is
The proper notations for sound exposure level using this reference are or , but the notations , , dBSEL, or dB<sub>SEL</sub> are very common, even if they are not accepted by the SI.