To mirror the surreal and inexplicable happenings on stage, Thomas Adès has created one of opera’s most colorful and mesmerizing scores, marshalling a wild array of instruments, techniques, and sound effects. The percussion section alone features xylophone, gongs, steel drum, anvil, washboard, spring coils, saucepans, a slammed door, and a drumhead-and-horsehair contraption called, for obvious reasons, a “lion’s roar.”
But the opera’s most consequential and unusual instrument is the ondes Martenot, an early electronic instrument invented in 1928 by French cellist and radio/telegraph operator Maurice Martenot. The name of the instrument translates as “Martenot waves,” and with it, Martenot combined his two areas of expertise, adapting radio transmission technology to produce audible soundwaves and creating a sophisticated keyboard-like interface for its operation. The player uses the right hand to control the pitch, either by depressing piano-like keys or by sliding a ring attached to a cable, called the “ribbon,” for a smoother, swooping sound. Both the keyboard and the ribbon allow the player to use vibrato as you would on the fingerboard of a violin or cello. Meanwhile, the left hand acts like the instrument’s bow, depressing a pressure-sensitive button that determines the volume and articulation of the notes. The left hand also operates a set of buttons that modify the instrument’s sound, from a very electronic character to an organ-like sound, or even highly distorted growls.
The expressive possibilities of the ondes Martenot have inspired a long line of musicians, from the great 20th-century French composer Olivier Messiaen to Jonny Greenwood of Radiohead, and thanks to its ethereal sound, it has often been used as the embodiment of a celestial or higher power. In The Exterminating Angel, the instrument can even be seen as the title character, giving voice to the unseen force responsible for the strange goings-on. At the Met, it will be played by international ondes Martenot specialist Cynthia Millar, for whom Adès wrote the part. Search for her on YouTube to get a taste of this intriguing instrument.