(1) Irregularities in the frequency response of a filter that has a nominally flat response in its passband, or
(2) irregularity in the value of DC voltage in a power supply which manifests itself as hum in the loudspeakers.
RMF Rich Music Format A type of midi file developed by Beatnik, inc., designed to be played back with its Beatnik Player. Player incorporates a custom sound set and allows for additional sounds to be embedded in the file, enabling greater control over layback than you have with the gm specification alone.