By the mid-20th century, frequency modulation (FM), a means of carrying sound, had been understood for decades and was being used to broadcast radio transmissions. FM synthesis was developed since 1967 at Stanford University, California, by John Chowning, . His was licensed to Japanese company Yamaha in 1973. The implementation commercialized by Yamaha (US Patent 4018121 Apr 1977 or U.S. Patent 4,018,121) , .
By the mid-20th century frequency modulation (FM) a means of carrying sound had been understood for decades and was being used to broadcast radio transmissions FM synthesis was developed since 1967 at Stanford University California by John Chowning  His was licensed to Japanese company Yamaha in 1973 The implementation commercialized by Yamaha (US Patent 4018121 Apr 1977 or US Patent 4018121)  