The Ondes Martenot was invented by Maurice Martenot (1898-1980), professor at
the Ecole Normale de Musique in Paris and later director of the Ecole d'Art
Martenot. Martenot, a cellist, manned a wireless station during WWII and
became interested in the sounds made by radio tubes. He met Leon Termen, the
inventor of the theremin, in 1923, and several years later produced the Ondes.
It was the first keyboard-based electronic instrument, and rapidly became
popular amongst experimental composers of the time, including Milhaud and
Honegger. One of the early virtuosi of the Ondes was Martenot's sister, Ginette
Martenot.
The Ondes combined great responsiveness to touch with distinctively
eerie and ethereal electronic tones and worked well as a solo instrument, for
example, in Marcel Landowski's chilling Jean de la peur. It was also
used as part of an orchestra, as in Olivier Messiaen's
Turangalila-Symphonie. Messiaen also composed an ensemble for eight
Ondes featuring his wife Yvonne Loriod, another virtuoso Ondes player. There are
still a few surviving instruments and a few modern players, Tristan Murail (who studied composition with Messiaen)
being the most notable.