What This Gesture Synth Actually Is
A gesture synth is not just a webcam gimmick that beeps when you wave. It is a precise harmonic chord synthesizer that maps real human anatomy onto polyphonic musical voicings. Your left hand selects scale degrees, harmonic root, and triad inversions, while your right hand dynamically sculpts the analog ladder filter cutoff, resonance frequency, and volume envelope.
Commonly searched online as a hand gesture synth, finger synth, or gesturesynth, this browser application brings the freedom of an omnichord or theremin directly into the modern web ecosystem using the Web Audio API and zero-latency client-side optical motion tracking.
How the Two Hands Work Together
Left Hand: Degree Voicings, Major and Minor
One raised finger triggers degree I (Tonic, e.g. C or G). Two raised fingers trigger degree ii (Supertonic). Three, four, and five cycle through the entire diatonic scale. Tilting your wrist slightly adjusts the chord quality between major, minor, suspended, and dominant 7th chords. This creates an intuitive physical instrument that allows musicians and gamers alike to perform intricate chord loops without needing a traditional piano keyboard.
Right Hand: Filter Sweeps, Octaves, and Timbre Dynamics
Your right hand acts as the expressive performance controller. Sweeping your hand horizontally across the webcam view adjusts a 24dB/octave resonant low-pass filter (LPF) from deep sub-bass frequencies up to screaming neon brilliance. Elevating your hand adjusts velocity and amplitude, while distinct hand poses transpose the entire synth up or down an octave.
How to Play Radiohead's "Creep" on Gesture Synth
One of the most famous progressions on modern gesture synthesizers is Radiohead’s timeless classic Creep. In the key of G, the song cycles through four iconic chords:
1. Select the G Major key in the top toolbar.
2. Raise 1 finger on the left for the G Major (I) chord.
3. Switch to 3 fingers for the harmonic B Major (III) lift.
4. Raise 4 fingers for C Major (IV).
5. Tilt your wrist outward on C to drop the third to C Minor (iv), feeling the dramatic emotional harmonic drop!