Audio Spectrum Analyzer

A live Fourier transform: incoming audio decomposed into how much energy sits at each frequency. Left is bass, right is treble, and the log spacing gives every octave equal width — so the musically-equal jumps from 100→200 Hz and 1k→2k Hz occupy equal screen distance.

The readout names the single loudest frequency. A whistle is nearly a pure tone, so its peak is its pitch. Voices and instruments stack harmonics, and sometimes a harmonic outweighs the fundamental — the display then names the harmonic's note. For serious instrument tuning, a dedicated tuner tracks the fundamental specifically.

Mains hum: electrical interference at your power grid's frequency (60 Hz in the Americas, 50 Hz most elsewhere), often with a harmonic at double. Fixes are physical — move the mic away from power supplies, try a different USB port or cable, or a ground-lift on audio interfaces.

Browsers apply processing to mic input by default; this tool requests raw input (echo cancellation, noise suppression, and auto-gain off) but operating systems sometimes add their own. Check your OS input level, and expect quiet rooms to show a low floor — that floor itself is useful data about your recording space.