Tone Generator
Play a steady tone from 20 Hz to 20 kHz. Dial in exact Hz or a musical note, pick sine, square, sawtooth, or triangle, and pan left or right — all in your browser.
Start quiet — a continuous pure tone is harder on your ears than music at the same volume, and high frequencies can sound faint while still being loud.
Pick a note instead of a number — A4 is 440 Hz; every note from C0 to B8 is a preset.
Sine for hearing tests and clean checks; square and sawtooth add harmonics that reveal rattles and distortion.
Pan fully left or right to test a single speaker, earbud, or ear.
A tone generator produces a single, pure, unchanging pitch — the audio equivalent of a test pattern. Use it to check whether a speaker plays, hunt rattles at a specific pitch, verify channel wiring, find your hearing limit above 15 kHz, or match a tinnitus pitch. Musicians use it as a pitch reference for tuning by ear; engineers use known frequencies to find room resonances and buzzing panels. The tone is synthesized in real time with the Web Audio API — nothing is downloaded or uploaded.
The frequency slider is logarithmic, so each octave takes equal distance — 20 to 40 Hz and 10 to 20 kHz feel the same under your finger. Type an exact Hz or step 1 Hz at a time; the readout shows the nearest note and its offset in cents (hundredths of a semitone). The balance slider pans left or right so you can test one speaker or one ear at a time.
Which waveform should I use?
All four share the same fundamental pitch but different overtones, so each suits a different job:
| Waveform | Sound | Best for |
|---|---|---|
| Sine | Smooth and pure — fundamental only, no overtones | Hearing tests, tinnitus matching, speaker checks |
| Square | Hollow and buzzy — strong odd harmonics | Hearing low pitches on small speakers; treble checks from a bass fundamental |
| Sawtooth | Bright and harsh — every harmonic present | Revealing rattles, resonances, and distortion |
| Triangle | Soft and flute-like — odd harmonics that fade fast | A gentler alternative to sine at low volume |
Common uses
- Tune by ear — set A4 = 440 Hz (or any concert pitch) with the note picker and match your instrument to it.
- Test speakers and headphones — pan fully left, then fully right, to confirm each side plays and channels are not swapped.
- Find your hearing limit — start at 8 kHz and step upward; most adults top out between 12 and 17 kHz.
- Match tinnitus — sweep slowly until the tone matches the ringing. (This page is not medical equipment.)
- Hunt rattles — sweep the low hundreds of hertz and listen for pitches where a shelf, panel, or car door buzzes.
- Hear acoustic beats — play on two devices a few Hz apart (e.g. 440 and 442) and listen for the slow pulse where the waves interfere.
Listen safely
Start every tone quiet, especially on headphones. A continuous pure tone packs all its energy at one frequency, so it fatigues — and at high volume harms — faster than music at the same loudness. Very low frequencies can also overdrive small speakers at volumes that do not sound loud. Raise volume slowly, and stop if you feel ringing or discomfort.