(1) Phasing is an effect on higher frequencies which make a whispering or ocean-like sound, produced by a device called a phaser, also called a phase-shifter. See flanging.
(2) Originally one of the defined MIDI Controller Change messages. It was assigned to the parameter in a synthesizer which alters the depth of the effect described as phasing. More recently, this message has been reassigned as one of five generalized Effects Depth messages.
See effects control.