A form of STEREOPHONIC or multi-channel reproduction in which the sound source is spread around the listener by the use of four tracks or CHANNELs in recording or transmission and the use of four (or more) LOUDSPEAKERs. Conventional music or speech may be recorded in this way, in which case the speakers behind the listener add REVERBERATION to the original sound or are simply out of PHASE with respect to the front ones; or new works may be composed in which all tracks carry original material.
A pre-recorded or simulated sound produced for a radio, television, film or theatrical program in order to suggest an actual sonic environment. The design of such sounds (often abbreviated as SFX), particularly when a complex acoustic environment is to be simulated, involves a thorough understanding of the structure of such a SOUNDSCAPE; that is, what sounds are representative and most significant, as well as which are necessary to create a given AMBIENCE and sense of ACOUSTIC SPACE.
The adjustment of the FREQUENCY of strings or pipes of musical instruments to conform to a given SCALE, or the adjustment of other instruments to such a tuned instrument.
Any quantity or body is in a state of oscillation when its value or motion is continually changing so that it passes through maximum and minimum values or positions. When a system, body or quantity is set in PERIODIC motion or vibration, it is said to be in oscillation.