Soundproofing glossary definition of ROOT-MEAN-SQUARE (RMS)

ROOT-MEAN-SQUARE (RMS) :

1. The root-mean-square value of a time-varying quantity is obtained by squaring the function at each instant, obtaining the average of the squared values over the interval of interest, and then taking the square root of this average. For a sine wave, if you multiply the RMS value by the square root of 2, or about l.41, you get the peak value of the wave. The RMS value, also called the effective value of the sound pressure, is the best measure of ordinary continuous sound, but the peak value is necessary for assessment of impulsive noises.
2. A term' describing the mathematical process of determining an 'average' value of a complex signal.