The ondes Martenot is an early electronic musical instrument invented by Maurice Martenot in 1928. It produces sound through oscillating electrical circuits and is known for its expressive capabilities, allowing musicians to create a wide range of tones and effects. The instrument features a keyboard and a ribbon controller, enabling players to glide between pitches. Often used in classical and contemporary music, the ondes Martenot has been featured in works by composers like Olivier Messiaen and Edgard Varèse. Its unique sound resembles that of a theremin, making it popular in film scores and avant-garde music, contributing to its distinctive place in the world of sound.