Tone Generator
A pure tone at any frequency from 1 to 22,000 Hz, in sine, square, triangle or sawtooth, with a twenty-second sweep from 20 Hz to 20 kHz. Type a frequency or slide to it on a logarithmic scale, pick a preset such as A 440 or 1 kHz, and read the nearest note, its period and its wavelength as you go. Every start and stop is ramped so nothing clicks, and above 60% volume the tone will not start without a second press, because hearing is the one thing here a wrong number can hurt. Everything runs in your browser; nothing is recorded or sent anywhere.
FrequencyA4 · sine · stopped
Stopped. Press Play to hear 440 Hz, sine, at 30%.
- A4
- 2.27 ms
- 78.0 cm
- the fundamental alone, no harmonics: the purest test tone
Start low, especially on headphones. A headphone driver sits against the ear, so a level that is merely loud from a speaker can be harmful from an earbud. The volume slider follows a perceptual curve, so 30% is a comfortable test level; above 60% the tone will not start on a single press, and while it is playing the level holds at the last confirmed value until you allow more. Every start and stop is ramped over 15 ms so nothing clicks.
Accuracy. The tone is produced by the browser's audio engine at the frequency shown, exact to the hertz; what reaches your ears depends on your speakers or headphones, which is why a hearing check here is not a test. Starts and stops are ramped over fifteen milliseconds so there is no click. The typed range is 1 to 22,000 Hz; the slider covers 20 to 20,000 Hz on a logarithmic scale, so each octave takes the same width.
Common questions
- Is it safe to play test tones through headphones?
- At a sensible level, yes, and the tool is built to keep the level sensible. Start low: the volume slider follows a perceptual curve, so 30% is a comfortable test level rather than a quiet one, and a headphone driver sits against the ear, where a level that is merely loud from a speaker can do harm. The tool cannot know how loud your headphones actually are for a given setting, which is why it never starts above 60% on a single press. Keep high-frequency and high-level tests short, and take the headphones off if you feel any discomfort.
- Why do I have to press Play twice above 60%?
- Because a loud tone that starts by accident is the one mistake here that cannot be undone. Up to 60% a single press plays. Above that, the first press only shows the level you are about to hear and asks you to press again; the second press is the confirmation, and that level is then remembered for the session. If you slide the volume higher while a tone is already playing, the level holds at the last confirmed value and an Allow button appears; nothing above 60% sounds until you have asked for it twice.
- Why can I not hear the 15 kHz or 17 kHz tone?
- Two ordinary reasons, and neither is a diagnosis. The upper limit of hearing falls with age: many adults over forty hear little or nothing at 17 kHz, and that is normal. The other reason is the equipment: laptop and phone speakers, and cheap earbuds, roll off steeply above 10 kHz, so the tone may be too quiet to notice even for a young listener. Try the 10 kHz preset and a proper pair of headphones before drawing any conclusion, and treat the result as curiosity, not a hearing test.
- Can I use this to test speakers?
- Yes, that is what the presets and the sweep are for. Play 1 kHz to check that each channel works and to set a reference level. Play 100 Hz and 20 Hz to hear how low a speaker or subwoofer really reaches; most small speakers produce almost nothing at 20 Hz. Run the sweep, which climbs from 20 Hz to 20 kHz over twenty seconds with every octave taking the same time, and listen for rattles, buzzes and sudden dips: a rattle at one frequency is usually a loose panel or grille resonating, and a dip is a crossover or a room cancellation.
- Why does the waveform matter?
- A sine wave is the fundamental frequency alone, with no harmonics, so it is the cleanest test tone and the one to use for hearing and frequency work. The other three add harmonics above the fundamental at set strengths: a square wave carries the odd harmonics, a triangle carries the odd harmonics much more weakly, and a sawtooth carries every harmonic, which is why it sounds brightest and harshest. Harmonics are what make a square wave at 440 Hz sound buzzy where a sine at 440 Hz sounds pure, and they are also why a sawtooth at high volume can be tiring: its energy spreads far above the frequency shown.
- What frequency does the note name refer to?
- The nearest note in equal temperament with A4 at 440 Hz, and how far off it the frequency is in cents, a cent being one hundredth of a semitone. 440 Hz is A4 exactly; 1,000 Hz is B5, 21 cents sharp. Middle C is 261.63 Hz. The names use sharps only, so a pitch never flips between two spellings as you slide.
- What range can it play, and why does the slider stop at 20 kHz?
- You can type any frequency from 1 to 22,000 Hz. The slider covers 20 Hz to 20 kHz, the usual span of human hearing, on a logarithmic scale so that each octave takes the same width; typing reaches the rest. Below about 20 Hz a tone is felt more than heard, and above 20 kHz it is inaudible to almost everyone, but both ends are still useful for exercising a subwoofer or checking that a system does not produce artefacts.
The tone is produced by the browser's audio engine at the frequency shown, exact to the hertz; what reaches your ears depends on your speakers or headphones, which is why a hearing check here is not a test. Starts and stops are ramped over fifteen milliseconds so there is no click.