The
ondes Martenot ( or ; , "Martenot waves"), also known as the
ondium Martenot,
Martenot and
ondes musicales, is an early
electronic musical instrument invented in 1928 by
Maurice Martenot. The original design was similar in sound to the
theremin. The sonic capabilities of the instrument were later expanded by the addition of timbral controls and switchable
loudspeakers.