The theremin's sound (as well as the ondes martenot) is just the beat frequency between two supersonic oscillators. While it is the electronic generation of so

The theremin's sound (as well as the ondes martenot) is just the beat frequency between two supersonic oscillators. While it is the electronic generation of sound, it doesn't really have the ability to modify the sound. Wether that a synthesizer or not, is up to your definition. Bob Moog's modular was also not the first (he and Buchla built their synths at about the same time). There was computer music being done on the RCA synthesizer in the 50s. Hugh Le Cain also did a lit of interesting stuff that predated Moog and Buchla.