#resonator

Helmholtz-resonator acoustics as an API, computed locally and deterministically. The frequency endpoint computes the resonant frequency of a Helmholtz resonator — a cavity with a neck, like a bottle or a ported speaker box — from the neck area (or diameter), the neck length and the cavity volume, f = (c/2π)·√(A/(V·L_eff)), adding the acoustic end correction (about 0.85·radius for a flanged end and 0.61·radius for a free end) so a short or open neck resonates lower than its physical length suggests. The design endpoint inverts the relation, V = A·c²/(L_eff·ω²), to give the cavity volume needed to tune a resonator or a muffler chamber to a target frequency. The port-tuning endpoint sizes a bass-reflex (vented loudspeaker) box port in practical audio units — from the box volume in litres and the port diameter in centimetres it gives the tuning frequency for a given port length, or the port length required for a target tuning frequency, using the 0.732·diameter end correction. Core endpoints use SI units; the speed of sound defaults to 343 m/s. Everything is computed locally and deterministically, so it is instant and private. Ideal for audio, loudspeaker-design, musical-instrument, muffler and acoustic-treatment app developers, bass-reflex and resonator tools, and acoustics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is Helmholtz resonance; for room reverberation use a reverberation API and for standing waves on strings and in pipes a standing-wave API.

api.oanor.com/helmholtz-api