440

Hz · A4

Hz

RMS −24.0 dBFS · peak −21.0 dBFS

Digital level. How loud it is at your ear also depends on your device volume and speakers. The output never peaks above −6 dBFS.

Left and right ears

A wiring check for two speakers: play a low tone from both. Wired in phase it sounds solid in the middle; with one flipped (or wired backwards) it sounds thin and the bass drops out.

Frequency sweep

Timed on the audio clock, so a long sweep stays accurate.

Log sweeps spend equal time per octave (the usual choice for speakers and rooms); linear sweeps cover equal hertz per second.

Second tone

Played in both ears at the same time (dial tones, intervals, beating). Uses the same waveform.

Hz
On / off pulses

Useful for finding a rattle or a loose connection by ear.

Fades and loudness

On: sine, square, triangle and sawtooth are set to the same RMS level, so switching waveform does not jump in volume. Off: they use the same swing, so a square is about 3 dB louder than a sine.

“Off” still ramps over 20 ms so starting and stopping never click.

Save as WAV

Made faster than real time with the same sound code as the live tone, so the file is what you hear (with your fades, pulses and limiter). Mono. Up to 180 s. A sweep played once ends when the sweep ends; noise repeats every 11 seconds or so.

Share or bookmark these settings

A link like ?f=440&w=sine opens with these settings. It never starts playing by itself.

Keeps playing with the screen locked on most phones. A tone you leave playing is a steady, loud-feeling signal: turn it down before you leave it.

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Nothing is uploaded. Just open it and start.

An online tone generator & hearing test

Free, no sign-up, no credit card, no trial. Play a precise tone or sweep, tune each ear separately, add noise, save a WAV or share a link, for testing speakers and headphones, finding rattles or generating a reference pitch, or run the careful hearing check.

Exact frequency

20 Hz to 20 kHz with decimals, 1 Hz, semitone and octave steps, and cents off the nearest note.

Sweeps, ears and noise

Log or linear sweeps, separate left and right tones, binaural beats, a second tone, pulses and white, pink or brown noise.

Careful hearing check

Volume step, faded tones in random order, silent catch rounds and each ear on its own. A screening, not a medical test.

Safe, private, saveable

Peaks capped at -6 dBFS, WAV download and share links, all on your device with nothing uploaded.

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Frequently asked questions

What can I use a tone generator for?
Playing a precise, steady frequency is useful for testing the range of speakers, headphones, or subwoofers, checking for rattles, tuning by ear, finding a resonant frequency in a room, or generating reference pitches. You can type an exact frequency (decimals like 432.5 work), step by a hertz, a semitone or an octave, and see how many cents you are from the nearest note.
How does the frequency sweep work?
Pick a start and end frequency and a time. A log sweep covers equal time per octave and is the usual choice for speakers and rooms; a linear sweep covers equal hertz per second. It can play once, loop, or go back and forth, and it is timed on the audio clock so a long sweep stays accurate. A sweep played once stops by itself.
What are the left/right, polarity and second-tone options?
You can give each ear its own frequency, or choose a binaural beat (the right ear plays the left frequency plus the beat). Use headphones for both. Flipping the polarity of the right channel is a wiring check for two speakers. A second tone plays in both ears at a level you set, for dial tones and interval tests. The beat is something your brain adds from the two pitches; this tool makes no claims that it changes mood, focus or sleep.
What do the different waveforms sound like?
A sine wave is the purest, smoothest tone. Square, triangle, and sawtooth waves add harmonics, so they sound progressively brighter and buzzier at the same frequency. By default the waveforms are matched in loudness so switching does not jump in volume; you can turn that off.
Is the level in dB real?
The level is the digital RMS level in dBFS, and the readout also shows the peak. Peaks never go above -6 dBFS, and a limiter sits last in the chain as a safety net. How loud it is at your ear still depends on your device volume and speakers, so the numbers are relative, not sound pressure.
Can I save a tone as a file or share it?
Yes. Save as WAV renders the tone, sweep or noise at the length (up to 3 minutes) and quality you choose, using the same sound code as the live tone, so the file matches what you hear. The noise is an 11-second recording that loops, so it repeats. Copy link makes a link such as ?f=440&w=sine that opens with those settings; it never starts playing by itself.
How does the hearing check work, and is it a medical test?
No, it is not a medical test and not an audiogram. First you raise a 1 kHz tone from silence until you just hear it, which sets the test level for your device and volume. Then short faded tones from 125 Hz to 18 kHz play in random order in one ear at a time, with silent rounds mixed in to catch guessing. Because headphones and volume are not calibrated, the result can only suggest how you hear on this setup; many people hear nothing above 15 to 17 kHz and many devices cannot play the highest or lowest tones. See a doctor or audiologist if you are worried about your hearing.
Any safety tips?
Start at a low volume, especially for high frequencies, noise and sweeps, and be careful with headphones. Loud tones can be uncomfortable or harmful. You see a short headphone warning before your first tone. The tone keeps playing with the screen locked on most phones, so turn it down before you leave it.
Is it free and private?
Yes. The tones are generated in your browser with the Web Audio API. Nothing is uploaded, and there is no sign-up. Your settings are kept on this device only.

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