03.08.2009
Ten times the logarithm to base 10 of the ratio of the mean square pressure of the portion of sound within a specified frequency band to the mean square pressure of the portion of a reference sound within the same frequency band
Ten times the logarithm to base 10 of the ratio of the mean square pressure of the portion of sound within a specified frequency band to the mean square pressure of the portion of a reference sound within the same frequency band