The first commercial digital sound synthesis method was Frequency Modulation (FM) synthesis [#!ChowningFM!#,#!ChowningAndBristow86!#,#!Chowning89!#], invented by John Chowning, the founding director of CCRMA. FM synthesis was discovered and initially developed in the 1970s [#!ChowningFM!#]. The technology was commercialized by Yamaha Corporation, resulting in the DX-7 (1983), the first commercial digital music synthesizer, and the OPL chipset, initially in the SoundBlaster PC sound card, and later a standard chipset required for ``SoundBlaster compatibility'' in computer multimedia support. The original pioneer patent expired in 1996, but additional patents were filed later. It is said that this technology lives on in cell-phone ring-tone synthesis.
As discussed more fully in [#!MDFT!#, p. 44], the formula for elementary FM synthesis is given by