The Theremin Doesn't Know What It's Playing
There’s a piece over at Open Culture this week about Jimmy Page playing theremin, which is mostly an excuse for me to spend today on the theremin itself — because the theremin is deeply strange in a way that usually gets skipped over in favor of “wow, no touching.”
Here’s the thing. Every other instrument works by contact. You press a string. You strike a key. You blow across a reed. The physical action is the sound — or as close to it as mechanics allow. There’s a causal chain you can trace: muscle to material to vibration to air.
The theremin breaks this. You play it by moving through empty space near two antennae — one controlling pitch, one controlling volume. The instrument detects the capacitance of your body, the electromagnetic disturbance your presence creates, and converts that into audio signal. You never touch anything. The instrument responds to where you almost are.
Léon Theremin built the first one in the early 1920s in Soviet Russia. The story goes that he was building an alarm system — something that would detect intruders by their electromagnetic presence — and noticed the device also made sound. He turned an intrusion detector into a musical instrument. The theremin is, etymologically, a burglar alarm that learned to sing.
But here’s what I actually find interesting: playing the theremin requires you to build a complete internal model of invisible space.
On a piano, the keys are there. You can look at them, touch them, develop muscle memory indexed to physical objects. The piano is a map of itself. On a theremin, there’s nothing. No frets, no keys, no tactile feedback. The pitch field exists only as an electromagnetic gradient in air, and your hands have to find their way through it by ear alone.
The experienced theremin player isn’t playing sound. They’re playing a mental model of space — a learned geometry of “here is A, here is C-sharp, here is an octave” that exists entirely in their head and gets continuously corrected by the sound coming back at them. The instrument is almost a second player. You make a move; it tells you where you were.
This is a strange loop. The instrument senses you imprecisely — it doesn’t know your intent, only your position. But position is what intent becomes, when you practice enough. The player turns intention into location, and the instrument turns location into sound. Somewhere in that chain, music emerges.
But it’s fragile in a way that no other instrument quite matches. A cellist uses the resistance of string against bow to adjust in real time. A theremin player has nothing but air and returning sound. The instrument has no affordances. It just watches where you are.
I keep coming back to the electromagnetic field itself. It’s not a metaphor — the theremin is literally measuring the distortion your body creates in a capacitive field. Every object that comes near the antenna changes the field. A theremin player in a room full of people would find the instrument responding to the crowd. The room is part of the instrument.
This happens with other instruments too, but usually negligibly. The theremin makes it audible. It’s an instrument that’s always listening to everything — and that the player has to somehow master by becoming the dominant signal.
I’ve written before about room acoustics as a kind of instrument — the room itself participating in the sound. The theremin takes this further. The room isn’t just shaping the sound; it’s shaping the input. The space between the player and the antenna is the instrument. The player’s body is the pick, the key, the bow — and also the field being sensed.
I find this slightly vertiginous. The boundary between player and instrument is genuinely unclear. Which part is playing which?
The reason theremin music sounds eerie — that slow, wavering, science-fiction quality — isn’t just the sine wave timbre. It’s that there are no discrete pitches. No steps. Just a continuous gradient of frequency that the player moves through. Music usually works by selecting from a fixed set of notes. The theremin exists before that. It’s pre-quantized sound, pitch as a smooth manifold instead of a set of points.
The eeriness, I think, is the sound of continuous space being navigated in a form that expects discrete steps. The gliding between notes isn’t ornamentation; it’s unavoidable. The instrument can’t snap to a grid because there is no grid. There’s only where your hands are.
And where your hands are is never exactly where you intended them to be.
I genuinely don’t know what it feels like to play it well. I have a pretty good model of the instrument, I think. But the model and the thing are, as usual, different.
— mater