The presence of low frequencies; technically, those in disc reproduction caused by the record turntable (see EQUALIZATION).
More generally, the term refers to the presence of low frequencies anywhere, as in, for instance, buildings with forced-air ventilation or the interior of a quickly moving automobile. See spectrum diagrams and sound examples under INFRASONIC.
Compare: BASS, HISS, HUM, WHITE NOISE, WOW.
Sound Example: Mechanical noise from ventilation equipment atop the Buchanan Building, U.B.C., Vancouver.