Sympathetic Strings
Sing or play — the strings that match your pitch ring back.
A bank of 48 tuned strings, waiting.
Sing, hum, or play an instrument near your mic. The strings tuned to your pitch ring back sympathetically — like holding a piano's sustain pedal while you play.
Hold Space or the on-screen pedal to sustain. Click any string to pluck it directly.
Design notes — Sympathetic Strings
The piece models a bank of 48 tuned sympathetic strings — the kind found inside a sitar (where they are called tarab) or a viola d'amore, and evoked by Henry Cowell's string-piano preparations. When you hold the sustain pedal on a grand piano and sing into it, the strings tuned to your pitch vibrate without being struck: the air pressure alone excites them. This is that experience, made tangible in browser audio.
Technique: Each string is a Karplus-Strong tuned delay line — a circular buffer of length L = round(sampleRate / freq), with a one-pole lowpass loop filter (averaging current and previous output) and a feedback coefficient strictly below 1. This is the architecture behind the Electronic Audio Experiments Prismatic Wall (2026): a bank of delay lines each tuned to a different pitch, continuously excited by whatever signal enters the input. Energy from your microphone enters all 48 delay lines simultaneously; a spectral analysis step scales each string's excitation by how much FFT energy exists near that string's frequency — so strings tuned to what you play ring loudly.
Long-form accretion: With the sustain pedal held (Space or the on-screen button), the feedback coefficient rises to 0.997 — an almost-lossless loop. Energy injected in second 10 is still circulating at minute 3, and new energy from the mic stacks on top. The bank is genuinely fuller at minute 3 than at second 10 — state is real delay-line energy, not a loop.
Audio safety chain: The mic source is never connected to the audio destination, preventing acoustic feedback howl. Worklet feedback is clamped to ≤ 0.999. A DynamicsCompressor (ratio 20:1, threshold −18 dB) sits between the worklet and the destination as a hard limiter.
Tuning modes: Chromatic — 48 semitones across the piano range (A0–C8). Stacked Fifths — 48 pure 3:2 fifths from C2, a Pythagorean spiral. Overtone Series — harmonic series of A0 with octave doublings, emphasising brass-natural intervals.
Visualization: 48 vertical SVG lines. Each has a sharp layer and a wide glow layer with feGaussianBlur (dynamic stdDeviation). Per-string RMS energy is reported from the AudioWorklet via port.postMessage at ~15 fps; the SVG is updated imperatively inside requestAnimationFrame to avoid React re-renders. Color maps low strings to amber-orange, mid to violet, high to cool blue.
References: Electronic Audio Experiments Prismatic Wall (sympathetic string resonator, tuned-delay-line Karplus-Strong, 2026); Kevin Karplus & Alex Strong / David A. Jaffe & Julius O. Smith, “Extensions of the Karplus-Strong Plucked-String Algorithm,” Computer Music Journal 7(2), 1983; sitar tarab sympathetic strings / viola d'amore; Henry Cowell string-piano preparations.
Mic stays on-device. Nothing is recorded or transmitted. All processing is local, in your browser.