Invented by Maurice Martenot, the Ondes Martenot is one of the earliest electronic musical instruments. It produces a sound similar to a Theremin but offers more control. The performer can play it using a standard keyboard or by pulling a metal ring attached to a wire, which allows for smooth, sweeping glissandi. It also features a sensitive wooden key on the left side that controls volume and expression. The instrument is famous for its eerie, haunting sound and was championed by classical composers like Olivier Messiaen. In the modern era, Jonny Greenwood of Radiohead popularized the instrument by using it on several albums and film scores. Because the original vacuum-tube models are fragile and rare, only a few specialized musicians in the world are trained to perform on them today.