| Definition: | logarithm of the ratio of a given time-mean-square standard-frequency-weighted sound pressure for a stated time period, to the square of the reference sound pressure of 20 μPa. Time-average sound level in decibels is ten times the logarithm to the base ten of that ratio
NOTE 1 – If a frequency weighting is not specified, the A-frequency weighting is understood.
NOTE 2 – In principle, exponential time weighting is not involved.
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