No keys. No contact. Pitch lives to the right, by the antenna; loudness rises as you climb; the tremor of your hand becomes vibrato. Move away and the aether goes silent.
move across the stage
the air is the string
How a hand becomes a note
Léon Theremin's 1920 aetherphone hides two radio oscillators. One runs fixed; the other is detuned by the capacitance of your hand near the antenna. Their beat — the difference between two frequencies you cannot hear — is the note. Here your cursor stands in for the hand: the closer it drifts to the rod, the higher the beat climbs.
The pitch axis is laddered in whole-number ratios — the perfect fifth at 3/2, the major third at 5/4 — so intervals ring without the faint sourness of equal temperament. The stage snaps gently toward each rung, yet never locks: you can bend a note flat by a hair, the way a player leans on a string.
The dark plate is scattered with fine sand. The tone shakes it — hard at the antinodes, still along the nodal lines — until the grains abandon the loud regions and pile up where the plate holds still. Louder shakes harder; higher pitch multiplies the lines. What you see is the literal standing wave of the sound you are making.