Online Pitch Tuner & Audio Frequency Detector (KO)

Acoustic instruments (guitars, violins, cellos, pianos) generate rich harmonic overtones that often produce higher peak amplitude than the fundamental frequency (f₀). Simple zero-crossing pitch trackers frequently produce octave jump errors when reading strong upper partials.

The Harmonic Product Spectrum (HPS) algorithm downsamples the linear FFT magnitude spectrum by integer compression ratios (1×, 2×, 3×, 4×) and multiplies them in the spectral domain. Inharmonic overtones cancel out, leaving an unmistakable peak at the true fundamental pitch. Sub-bin parabolic interpolation provides sub-cent accuracy down to 0.1 Hz resolution.

Standard modern international concert pitch is calibrated to A4 = 440 Hz per the ISO 16:1975 Standard Tuning Frequency. Scientific and historical tunings frequently use A4 = 432 Hz (Verdi pitch) or A4 = 442 Hz for modern European symphonies.

Each instrument preset incorporates its signature physical acoustic modeling: plucked acoustic guitar strings with harmonic damping, deep punchy electric bass resonance, bowed violin/cello sustain with natural vibrato and wood formants, bright double-string mandolin chime, and banjo membrane twang.