Quick answer
The ondes Martenot are one of the world's first electronic musical instruments, invented by Maurice Martenot in 1928. They produce sound with electronic oscillators and are controlled with a keyboard and a sliding ring on a ribbon, which enables continuous glissandos and very expressive vibrato. Their ghostly, vocal timbre is a cousin of the theremin, but with far greater pitch precision.
What are the ondes Martenot?
The ondes Martenot are a monophonic electronic musical instrument (one note at a time) invented by French musician and engineer Maurice Martenot and first performed in Paris in 1928. They are among the absolute pioneers of electronic music, contemporary with the theremin (1920) and predating synthesisers by decades.
Unlike a piano or guitar, where sound originates in a string or hammer, the ondes Martenot generate sound with electronic oscillators (originally vacuum tubes). This gives the instrument a pure, continuous, "bodiless" timbre that is immediately recognisable — many describe it as a distant human voice or a supernatural sound.
The instrument has been taught officially at the Paris Conservatoire since the mid-20th century, which explains why so many French scores include it. It is simultaneously a piece of technological history and a fully active concert instrument.
If you are drawn to instruments that break the rules, the ondes Martenot share that enchanting strangeness with the theremin, the stylophone or the otamatone — all expressive electronic instruments played in unconventional ways.
How it works: keyboard, ribbon and the expression drawer
What makes the ondes Martenot unique is its system of control using both hands simultaneously:
The keyboard and ribbon (right hand)
The right hand has two modes of playing. It can press a standard keyboard (au clavier mode) — each key also moves sideways to produce natural vibrato with the finger. Or it can use ribbon mode (au ruban): the player slides a metal ring (la bague) worn on the finger along a taut ribbon parallel to the keyboard, generating continuous glissandos with no steps, like a perfectly tuned siren.
The intensity key (left hand)
The left hand controls the touche d'intensité, a pressure-sensitive key housed in a drawer on the left. It produces no pitch: it governs the volume and attack of each sound in real time. Thanks to it, the musician can make a note emerge from silence, swell, vibrate and fade away with extraordinary dynamic control. This "breath" of the sound is the great distinction from the theremin.
The diffuseurs
Sound comes out through specialist speakers (diffuseurs). The most celebrated is the Palme: a lyre-shaped diffuser with sympathetically resonating strings, adding a harmonic halo to the timbre. Others use a metal gong or plate for natural reverb. Changing diffuseur completely transforms the colour of the instrument.
Ondes Martenot vs theremin: what's the difference?
The comparison is inevitable because both were born in the 1920s and share that ethereal timbre. But they are played very differently:
| Feature | Ondes Martenot | Theremin |
|---|---|---|
| Year | 1928 | 1920 |
| Pitch control | Keyboard + ribbon ring | No contact (antennas) |
| Intonation accuracy | High | Very difficult |
| Dynamics control | Intensity key | Volume antenna |
| Learning curve | Medium–high | High |
In short: the theremin is more visually spectacular (played in the air), but the ondes Martenot offer far more control by combining physical keyboard, ribbon for glissandos and a dedicated dynamics key. If you want to start with an electronic instrument of this kind without spending a fortune, read our theremin guide or explore the stylophone.
History: from 1928 to Radiohead
Maurice Martenot, a cellist and radio operator during the First World War, became fascinated by the pure sounds of vacuum tubes in radio equipment. That experience led him to design an instrument combining the expressiveness of an acoustic instrument with the novelty of electronic sound. He patented it and presented it in 1928.
Composer Olivier Messiaen became its great champion: he used it centrally in his monumental Turangalîla-Symphonie (1948), where the ondes Martenot provides that soaring timbre that floats above the entire orchestra. Since then, dozens of 20th-century composers have written for the instrument.
Cinema adopted it early too: its "ghostly" timbre was perfect for 1950s and 1960s science-fiction and horror. In the 21st century it enjoyed a second life thanks to Jonny Greenwood, guitarist of Radiohead, who has used it on band albums and film scores, returning the instrument to popular culture.
Can you play or buy one today?
Original instruments are extremely rare and expensive — practically museum and collector pieces. That is why modern recreations have emerged:
- Physical replicas such as the Ondéa, which reproduce the keyboard, ribbon and intensity key with modern electronics.
- Software emulations (VST/AU plugins) that recreate the sound for computer music production.
- Ribbon controllers and modern synthesisers with a touch strip that allow Martenot-style glissandos.
If what attracts you is experimenting with expressive electronic sound without spending much, there are far more accessible instruments to start with: the theremin, the stylophone or the delightful otamatone all share that "rare electronic instrument" spirit at a beginner-friendly price.
Frequently asked questions
What are the ondes Martenot?
One of the earliest electronic instruments, invented by Maurice Martenot in 1928. They generate sound with electronic oscillators and are controlled with a keyboard and a sliding ring on a ribbon, enabling glissandos and expressive vibrato.
How do they differ from the theremin?
The theremin is played without touching anything, by moving hands near two antennas, and is very hard to keep in tune. The ondes Martenot have a keyboard and ribbon, so pitch is far more precise, plus a dedicated key for volume and attack control.
How are they played?
With both hands: the right presses the keyboard or slides the ring along the ribbon; the left regulates volume and attack with the intensity key. Special speakers (diffuseurs) such as the Palme — with sympathetically resonating strings — colour the timbre.
Where have they been used?
In classical music (Messiaen, Turangalîla-Symphonie), film scores and contemporary pop-rock, especially with Jonny Greenwood (Radiohead). Taught at the Paris Conservatoire.
Can you buy one today?
Originals are museum pieces. Modern recreations (such as the Ondéa) and software emulations exist. For expressive electronic sound on a budget, the theremin, stylophone or otamatone are accessible alternatives.
Why do they sound so ghostly?
Pure electronic oscillators combined with fine vibrato control (via the ring on the ribbon) and dynamic shaping (via the intensity key) produce a continuous, vocal, sliding sound without percussive attacks — evoking distant voices or supernatural atmospheres.