Tone Generator
Play any frequency from 20 Hz to 20 kHz — sine, square, triangle, saw.
About this generator
A signal generator in your browser: type a frequency or sweep the log-scale slider from 20 Hz to 20 kHz, pick a waveform, and play — the tone follows the slider live, and the readout shows the nearest musical note (440 Hz is A4 exactly). Presets jump to the useful landmarks. Start quiet: pure tones, especially high ones, are louder than they sound.
What the frequencies are for
Tuning: A4 = 440 Hz is concert pitch — tune to the beat between your instrument and the tone vanishing. Speaker testing: sweep 30–100 Hz to hear where a subwoofer really gives up, and 8–15 kHz for tweeters; buzzing at specific low frequencies is furniture resonating, a genuinely useful diagnosis. Hearing ceiling: sweep upward and note where the tone vanishes — most adults land between 12 and 17 kHz, and the hearing test makes a proper session of it (with the mosquito-tone story explaining why teenagers hear what you can't). Waveforms matter too: sine is the pure test signal; square and saw carry harmonics, which is why they sound rich at the same pitch — the speaker test covers channel checks.
Frequently asked questions
What frequency should I tune to?
A4 = 440 Hz, the concert-pitch standard — the preset jumps straight there. Tune until the beating between your instrument and the tone disappears.
Why can't I hear the high frequencies?
Age-related high-frequency loss is universal: most adults top out between 12 and 17 kHz, teenagers near 18-19. It's normal, and everyday sound lives far below the lost range.
Why do square and sawtooth sound harsher than sine?
They contain harmonics — energy at multiples of the base frequency — while a sine is the base alone. Same pitch, more spectrum, hence the buzz.
Can this test my subwoofer?
Yes — sweep 20-100 Hz at moderate volume. Where the output fades tells you the sub's real floor, and any rattling is something in the room resonating, not necessarily the speaker.