Tone Generator
Play a pure test tone from 1 Hz to 22 kHz in sine, square, sawtooth or triangle wave. Tune to 440 Hz, play two tones at once and watch the waveform live.
Arrow keys: ±1 Hz. Hold Shift for ±10 Hz, Alt for ±0.1 Hz.
Start quiet and turn up slowly. Square and sawtooth waves sound louder than a sine, and you may not hear very high or very low tones even when they are loud enough to strain your ears or speakers.
Picking a note sets an equal-tempered pitch. Changing the reference retunes the current note.
Included because people search for them. There is no good evidence that these frequencies heal anything.
What you hear depends on your speakers. Laptop and phone speakers barely play below 100 Hz.
What to do with a tone generator
Common uses
Musicians tune to 440 Hz (A4), or 442 Hz for many orchestras. For speakers and subwoofers, sweep the slider down slowly and note where the bass fades or a panel starts to buzz: a sub rated to 25 Hz should still move air there, and rattles point to loose trim or a damaged cone. In a room, slow sweeps between 30 and 200 Hz reveal resonances, where one note booms and the next nearly vanishes. Some people with tinnitus use a tone to match the pitch they hear and describe it to an audiologist. That is a starting point for a conversation with a doctor, not a diagnosis or a treatment.
Sine, square, sawtooth and triangle
A sine is a single frequency with no harmonics, which is why it is used for testing. A triangle adds faint odd harmonics and sounds a little brighter. A square wave has strong odd harmonics (3×, 5×, 7× the base frequency) and sounds hollow and buzzy, and a sawtooth contains every harmonic, so it is the harshest. Those harmonics mean a 5 kHz square wave also puts energy at 15 kHz and 25 kHz, so use a sine when you want to test one frequency at a time.
Safety
Start at a low volume, especially with headphones, and raise it slowly. Hearing is least sensitive at the extremes, so a 15 kHz or 30 Hz tone can be loud enough to harm your ears before it seems loud. A long, loud sine at the bottom or top of the range can also overheat a tweeter or push a woofer past its limits. Use the auto stop if you leave a tone running.
BS check: healing frequencies
Videos promise that 528 Hz repairs DNA, that 432 Hz is the natural tuning of the universe, or that binaural beats replace sleep pills. No good evidence backs any of this. The Solfeggio numbers were popularised by numerology books in the 1990s, not by ancient science, and the small binaural beat studies show weak and inconsistent effects. A quiet, steady tone can be relaxing, as can rain sounds. That is the whole effect.
Related tools
Sweep your speakers automatically with the frequency response test, check the range you can hear with the hearing test, confirm left and right channels with the sound test, or check stereo, bass and imaging on your headphones with the headphone test.
Frequently asked questions
Which waveforms can I play?
Sine, square, sawtooth and triangle. Pressing one of those buttons sets the oscillator to that shape, including while a tone is already playing. A sine is a single frequency. A triangle is a bit brighter, a square is buzzy and a sawtooth is harsher. At the same slider position, square is played at 45% of the sine gain, sawtooth at 55% and triangle at 90%.
How do I stop the tone?
Press Stop, or press Space when you are not in the frequency box or a dropdown. Auto stop can end it after 1, 2, 5, 10, 15, 30 or 60 minutes. Stop silences the oscillator and suspends the audio context. Leaving the page silences it and closes the context. Volume 0 is silent, but the tone stays running until you press Stop or leave.
Why is it quiet when the page opens?
Nothing plays on load. Browsers block audio until a click or a key press. Press Play, or Space outside a field, and that gesture resumes the audio context before the oscillator starts. The page does not start a tone by itself.
What happens at volume 0?
The volume slider runs from 0 to 100 and starts at 15. Loudness is the square of the slider percent, so the quiet end moves in smaller steps. At 0 the gain is set straight to 0, which is silence. A fade down to 0 would never quite arrive, so the zero mark is an exact value.
Does the big number match the tone?
Yes. The large hertz figure is the oscillator frequency, from 1 Hz to 22,000 Hz. The slider, step buttons, number box, note picks and presets set that frequency directly, so a glide cannot leave the pitch off the number. With dual tone on, the second oscillator is the second frequency shown under the number: the first tone plus the offset, and never past 22,000 Hz.
Does this measure hearing or speakers?
No. The page only generates the tone you set and draws that signal on the oscilloscope. It does not use the microphone, score your hearing or measure a speaker. High and low tones can still be hard to hear on a laptop or phone, so start at a low volume.