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Inventing Electronic Music: the Ondes Martenot

Making Waves into the 21st Century

Naomi Mitchell · 01/03/25

Continuing next in our series of the history of synthesis, we move from Leon Termen’s invention of the theremin to the ondes Martenot. Maurice Martenot was a cellist who worked as a radio operator for the French army during WW1. Martenot became interested in the pure electronics sound of the radios he worked with, the ways that sine waves sounded on their own and when combined with different frequencies.

Ondes Martenot Overview

Like many at the time, Maurice Martenot was fascinated by the Theremin. However, Martenot was trained as a cellist and did not come at the process of inventing a new kind of instrument from an engineering-centric standpoint. After meeting the Russian inventor in 1923, he worked for several years designing an instrument that would become known as the ondes Martenot: translated roughly, Martenot’s waves. Patented in 1928 under the name Perfectionnement aux instruments de musique électriques or "improvements to electronic music instruments," Martenot took Termen’s revolutionary idea for an electronic instrument from the realm of flailing your hands in the air around a pair of antennae and to a metal wire and ring along a fixed line, more akin to traditional instruments.

[Above: a video from the Seattle Symphony, in which ondist Cynthia Miller offers a guided tour of her instrument.]

Sounds are created by heterodyning oscillators made from vacuum tubes, as popularized by the theremin. In contrast to the simple sine-like tones of the theremin, the ondes Martenot includes a number of different basic waveforms, each with their own character and use case. The first version of the ondes Martenot lacked a mechanical keyboard, which would not be added for several iterations. A wire sits below the keybed, running across the length of the instrument suspended above a metal bar. A ring is attached to the wire, which the ondist (an ondes Martenot player) uses to play notes, indicated by a series of holes (white notes) and bumps (black notes) in the bar. However, you can also play notes above the bar for full variable control over the pitch of the instrument. By attaching the ring to a discrete wire, the notes are more easily organized into scales, but small movements in the position of an ondist’s hand cause vibrato and pitch bends. Later versions of the ondes Martenot added a physical mechanical keyboard along with the wire and ring, and not just a painted reference. The keyboard on many ondes is six octaves, with a switch to transpose the keyboard up an octave.

Like the theremin, notes are controlled with the right hand, and the volume articulation with the left. The articulation is controlled by an ingenious method that allows for dynamic and expressive control of notes. A small lever, called the touche d’intensité—roughly "intensity key," sometimes shortened to touche—may be likened to the bow of the instrument, fitting as Martenot was a cellist. A bag sits under the lever. This contains graphite, a conductor, and mica, a resistant element, which are manipulated by the lever in order to change the articulation. There is an emphasis on the player controlling all the aspects of the sound. Because there is no LFO or envelope generators to automate the dynamics or vibrato of the instrument, it is more akin to a traditional instrument. Modern versions of the instrument use magnets, pressure sensors, or capacitive touch sensors in lieu of the bag of powders.

Martenot created several unique diffusers (specialized loudspeakers) for the device. One simply amplified the sound, while the others added resonators in order to further shape the sound.

One, the metallique, included a gong with a metal pin that passed through the gong that produced the vibration, turning the orchestral gong into a speaker. Another, the fittingly-named palme, was shaped like a palm frond, with a series of tuned strings to act as the resonator. These act as sympathetic strings, which are not directly played, but capture the resonant frequencies of the sound passing through them, producing harmonically related vibration. The strings were of variable length, allowing a performer or composer to adjust the character of the reverberation. Any combination of the loudspeakers could be used at once, with a dial that controls how much signal passes to each loudspeaker, a bit like a dry/wet control on an effect such as delay or reverb.

Ondes Martenot & Olivier Messiaen

The Ondes Martenot is one of the few electronic instruments to see considerable time as part of the orchestra, and is still used to this day. Martenot would eventually work as a professor at the Paris Conservatory, teaching future ondists how to play the instrument he designed and built himself. It never saw mass market, as units were built to order. The Theremin was simple enough in its implementation to be built by hobbyists, while Martenot closely guarded some of the elements of his design to his grave.

The unique tones and dynamic and expressive playing possibilities of the ondes Martenot captured the imagination of composers, most notably Olivier Messiaen. In 1937, he wrote FĂªte des Belles Eaux for six ondes Martenots for the Exposition Internationale des Arts et Techniques dans la Vie Moderne, or the International Exposition of Art and Technology in Modern Life, known colloquially as the French Exposition.

The French government commissioned 20 musicians to compose music for the exposition, including Messiaen, who was tasked with writing music to accompany a firework and fountain show on the Seine. Knowing that his music was going to be amplified through loudspeakers to the crowd, he decided to embrace that electronic element and chose to write the piece for a sextet of ondes Martenots. The fireworks, fountains, and music were precisely synchronized, with Messiaen receiving extensive notes about the timing and movements of the visual elements. Of the performance, he wrote:

The music reflects the mystery of the night, the funereal aspect of the deep water, and the joyous, playful, carefree character of the fireworks. The jets of water, by contrast, seemed to me to be either fierce and terrible, or dream-like and contemplative. It is this last mood that predominates, and in the most worthwhile moments of FĂªtes des belles eaux—when, on two occasions, the jets of water shoot up to a great height—a long, slow phrase is heard, almost a prayer; this turns the water into a symbol of grace and eternity…

Messiaen’s Trois petites liturgies de la présence divine used the ondes Martenot in its third movement, his first time using it within the context of a larger orchestral piece. He would go on to write several more pieces using the instrument, helping to showcase this unique instrument within the context of classical orchestral music.

Modern Perspectives & Interpretations

While the timbres are distinctively electronically produced, the simple waveforms of the ondes Martenot and the articulation of the players make it sound much more like a string or woodwind quartet than any electronic music up until Switched-On Bach. But even Wendy Carlos’s masterpiece still decidedly sounds like a work of electronic synthesizer music.

Maurice Martenot’s innovation of decoupling the pitch and the articulation allows it to be played much more expressively than the organ-style keyboard found on the Moog modular and generations of synthesizers that came after. The focus is less on creating interesting timbres of the waveforms through processing such as filtering and wave shaping, and much more on the act of playing in much the same way as an acoustic instrument. Part of the allure of the synthesizer is the ability to create a vast array of electronic sounds, to shape the harmonic character of a sound and create tones and timbres that could not exist in an acoustic instrument. But the interaction of performer and instrument is often abstracted away. Organ-style keyboards are still the dominant method of manually playing a synthesizer, but pianos and organs only account for a small subsection of all the acoustic instruments. While the helpful layout of organizing notes within a two-tone system makes sense for visually recognizing notes within a 12 tone scale, there are plenty of other ways a performer could interact with an instrument.

I had a chance to sit down with a modern recreation of a later iteration of the ondes Martenot VCO, made by Therevox. While this version was modeled after a later version that changed the design from vacuum tubes to solid-state electronics, it is still modeled after the signature sound. So, let's talk about the sound generator—its various waveforms and sonic character.

[Above: the Therevox Ondes VCO]

The Onde waveform is a sine wave, which is more harmonically pure in the upper ranges of its frequency range. In lower octaves, the smooth edges of the sinewave become slightly less rounded, introducing more harmonic character when tuned lower. While this isn’t as clear when the waveform is more or less synchronized to a stable frequency on an oscilloscope, it becomes more obvious when adjusting the pitch outside of those regions of stability. The Octaviant waveform is derived from this sine wave using a process called rectification in order to introduce a secondary harmonic. Rectification is a process where the negative-going portion of a waveform is chopped off and folded over on itself, both doubling the frequency and adding harmonics where the smooth sine wave is sharply folded. Creux takes the triangle core of the oscillator and chops off the top and bottom of the waveform, creating a trapezoid-like shape with a slight angle instead of perfectly horizontal lines.

Nasillard is a pulse waveform with an incredibly narrow duty cycle. If you compare a square wave to a gate signal, this output would be equivalent to a trigger signal. It is decidedly more harmonically complex, particularly in higher harmonics, than the Gambe, a pulse waveform with a 35/65% duty cycle. Square/pulse waveforms are often used to synthesize a clarinet-like sound, particularly useful in a symphony setting. Petit Gambe, takes the Gambe waveform and adds a low pass filter to it, smoothing out the rough edges of the pulse waveform. Tutti is a mix of the six waveforms, creating the most harmonically complex and irregular shape as the different waveforms mix and cancel parts of eachother out.

This adaptation of the instrument leaves out the souffle timbre, which many people refer to as white noise—but it is actually a softer pink noise. Pink noise is often used in place of white noise, as the filtering on it makes it sound less harsh than proper white noise. See our article all about noise for more information on the different kinds of noise, roughly approximated to the different wavelengths of light.

Expressive E is a French company that makes interfaces and instruments that try to capture the feeling and freedom of playing an acoustic instrument, coupled with the power and flexibility of electronic sounds. Work on the Touche began while at the Pierre and Marie Curie University, where they studied the mechanics of the ondes Martenot. Inspired by the touche on the ondes Martenot, they updated the design, replacing the simplistic but ingenious method of graphite and mica with silicone and microcontrollers. The result takes that building block and updates it for modern synthesis techniques. This new iteration offers control more akin to a joystick, with each direction able to be mapped to different parameters, but can also be pressed to trigger notes. The original version is equipped to send gestural data over as MIDI messages, analog CV signals, or over a wired USB connection. The slimmed down lighter version of the Touché, the Touché SE (software edition), is intended to be used with DAWs, and only includes a USB connection. A companion software adds deep control over every parameter of the Touche. A library of presets provided by Expressive E are mapped out to common synthesizer parameters, making it a breeze to integrate with a variety of different use cases. Four 3.5mm CV jacks with a range up to +/-10V allow users to easily route different axes to any parameter in their modular or semi-modular synthesizers. While it is quite a task to get an actual ondes Martenot in the 2020s, Expressive E brings one of its most groundbreaking features to musicians of all levels.

The ondes Martenot is a brilliant and compelling instrument—which, thanks to its robust literature and a tightly-knit network of performers, instrument makers, composers, and hobbyists—is still persisting. You can hear it in music by celebrated composers such as Messiaen, Edgard Varèse, Tristan Murail, and others; you can hear it in popular music by Radiohead; and you can find its likeness emulated in countless modern instruments. Some modern boutique instrument makers do still produce complete ondes-inspired instruments suitable for serious players, though of course, its concepts can be embraced in many ways.

If you want to learn more about the ondes Martenot, we'd strongly suggest the Caroline Martel documentary Wavemakers (2012). We'd also suggest reading Dorien Schampaert's 2018 PhD thesis Ondes Martenot Network in the Twenty-First Century: The Co-Construction of the Ondes Martenot and its Users, which takes a Social Construction of Technology (SCOT)-inspired approach to documenting the often-precarious evolving state of the instrument's history and legacy.