Crest Factor

The term used to represent the ratio of the peak (crest) value to the RMS value of a waveform. For example, a sine wave has a crest factor of 1.4 (or 3 dB), since the peak value equals 1.414 times the RMS value. Music has a wide crest factor range of 4-10 (or 12-20 dB). This means that music peaks can be 12-20 dB higher than the RMS value, which is why headroom is so important in recording and audio design.