Electronic music encompasses a great variety of methods and styles, though it is all produced through electronic technology. Starting in the late 1920s, early electronic music was produced on the Theremin, the Ondes Martenot, and other instruments that produced tones that could be raised or lowered through physical means. Wire and tape recording in the 1940s and '50s permitted the development of musique concrète, which involved altering acoustic sounds and rearranging them in recorded form as musical ideas. Since the 1960s, synthesizers, computers, and digital recording have been essential tools in creating contemporary electronic music, and its diffusion through academic and commercial studios has made it a permanent part of modern classical concert music and experimental works, as well as film and TV soundtracks, popular songs, and dance genres.