Wow

A slow fluctuation in pitch due to mechanical faults in analog recording or reproducing equipment. The rate of wow is slower than that of flutter, and is usually in the range of 1-5 Hz.

With sustained or slow moving sounds, wow can be detected as a slow oscillation of pitch when the frequency variation is about 0.25%. With shorter sounds, the ear can only detect much greater variations.

Compare: Frequency Modulation, Rumble, Tape Recorder, Vibrato.