Theremin is played without the hands touching it

In front of a theremin, the musician seems to shape a melody in the void, without touch or rope. His hands move near two metal elements often called antennas. The distance between them and the body influences the circuits of the instrument, allowing the sound to be controlled without direct contact.

The University of Maryland explains these elements as parts of variable capacitors. The hand plays the role of another conductive surface; its displacement changes the electrical capacity of the whole. One part of the device controls the height of the sound, another its amplitude. The signal is then amplified and sent to a speaker that produces the audible sound.

The device does not magically recognize a musical intention. The gesture changes a physical magnitude, then the electronics translate it into sound. The absence of a keyboard does not eliminate the need to control one’s movements. It transforms the relationship between the body and the instrument: the space around the case becomes a play area.