(1) The process of following the envelope of a signal’s waveform, as in a level meter of any type.
(2) In describing the performance of a phonograph stylus or other transducer, the measure of it s ability to precisely follow the instantaneous waveform of the applied signal, be it mechanical, e.g., a record groove, acoustic, or electrical.
(3) A synonym for over-dubbing.
(4) See double-tracking