The ondes Martenot or ondes musicales is an early electronic musical instrument. It is played with a keyboard as well as by moving a ring along a wire, creating "wavering" sounds similar to a theremin. A player of the ondes martenot is called an ondist.

How does an ondes martenot work?

How does it work? The main interface of the ondes martenot was originally a metal ring, worn on the player's right index finger that, when slid up and down a wire, would create theremin-like sweeps in tone (through oscillations in vacuum tubes).

What is the primary difference between the theremin and ondes martenot?

The ondes martenot is a theremin-like musical instrument; instead of waving your hands around aerials on the theremin, the ondes uses a small ring attached to the player's finger on a wire loop and a volume lever. The ondes isn't a common instrument by any means, but Radiohead uses one several in any event.