Perf Buzz

Perf buzz is the sound created when the film sprocket perforations of an optical soundtrack are played back as if they were part of the audio program. Perf buzz can be printed into an optical soundtrack, or it can occur when a projector or optical dubber is not properly aligned and reads the perforations as program. 35mm film played at 24 frames per second will create a perf buzz at 96Hz and sometimes at the first octave harmonic of 192Hz.