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Tone Generator

Play a pure tone at any frequency, for tuning, testing speakers or checking your hearing.

Maintained by BrowserTools · Last updated 2026-09-29

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A tone generator plays a steady sound at exactly the frequency you choose. This one covers the whole range from 1 Hz to 22 kHz (the upper end depends on your device's sample rate) with a logarithmic slider that gives every octave the same space, a number box for exact values and fine buttons that step by anything from 0.01 Hz to 1 kHz. You can pick a note by name, with A4 set to 440 Hz or any other reference between 400 and 480 Hz, and the readout always shows the nearest note and how many cents you are away from it. Four waveforms are available: sine for a pure tone, and square, sawtooth and triangle when you want harmonics, for example to test how a speaker handles a richer signal.

Frequently asked questions

What frequency range can I play?
From 1 Hz to 22 kHz. The highest frequency a browser can produce is half its audio sample rate, so on a device running at 44.1 kHz the top is just over 22 kHz and the tool limits it slightly below that. Whether you can actually hear the extremes depends on your speakers: small laptop and phone speakers produce little below about 150 Hz.
Which waveform should I use?
Use sine for tuning, hearing checks and anything where you want a single pure frequency. Square, sawtooth and triangle waves add harmonics at multiples of the base frequency; they sound buzzier and are handy for testing distortion or making a tone easier to hear on small speakers. The tool lowers the level of square and sawtooth waves so they are not much louder than a sine.
How do I test my speakers or subwoofer?
Use the sweep mode with a logarithmic curve, for example 20 Hz to 20 kHz over 20 to 30 seconds at a moderate volume. Listen for rattles, buzzing or points where the sound suddenly drops or booms, which point to resonances or room modes. For a subwoofer, sweep 20 to 200 Hz. Pink noise is better for comparing the overall balance of two speakers.
How does the dual tone or binaural mode work?
It plays one oscillator in the left channel and another in the right. With headphones, two slightly different frequencies such as 200 and 210 Hz are perceived as a slow 10 Hz pulsing called a binaural beat. Setting both to the same frequency is a quick way to confirm that left and right are wired correctly and balanced.
What is the difference between white, pink and brown noise?
White noise has equal power at every frequency, so it sounds bright and hissy because most of the audible hertz are in the treble. Pink noise has equal power in every octave and sounds more natural; it is the standard test signal for audio systems. Brown noise has even more low end and sounds like a deep rumble.
Is the hearing test accurate?
It is a rough check, not a medical test. The result depends on your headphones or speakers, the volume, background noise and your reaction time, and many consumer headphones roll off above 16 kHz. Repeating it a few times gives a more stable figure. For an actual hearing assessment see an audiologist.
Can a tone generator damage my hearing?
Yes, if it is too loud or played for a long time. Pure tones concentrate all their energy at one frequency and very high tones can be loud without seeming so. Start with the volume low, raise it slowly and avoid long sessions with headphones at high volume.
Why do I hear a click when some tone generators stop?
Cutting a waveform off abruptly creates a sudden jump in the signal, which the speaker reproduces as a click. This tool fades the level in and out over a few tens of milliseconds on every start and stop, which removes the click without being noticeable as a fade.

About Tone Generator

Beyond single tones there are modes for common audio jobs. The frequency sweep glides from a start to an end frequency over the time you set, on a linear or logarithmic curve, which is the classic way to find rattles, resonances and dips in a room or a pair of speakers. The dual tone mode sends one frequency to the left ear and another to the right, useful for checking that channels are not swapped and for listening to binaural beats with headphones. The noise generator produces white, pink and brown noise: pink noise is the standard signal for balancing speakers and sound systems, while brown noise is popular for masking background sounds. Every start and stop uses a short volume ramp, so there is no click even when you stop in the middle of a waveform.

The hearing range test sweeps slowly upwards from 8 kHz and records the frequency at which you press I can't hear it. Most adults stop hearing somewhere between 12 and 17 kHz, and the limit drops gradually with age, but the result says as much about your headphones or speakers as about your ears, so it is a curiosity, not a diagnosis. Keep the volume low: the default level is deliberately quiet, and high frequencies or square waves can be uncomfortable or harmful at high volume, especially through headphones. Everything is generated live in your browser with the Web Audio API; nothing is downloaded or recorded.

From tuning forks to 440 Hz

The tuning fork was invented in 1711 by John Shore, a trumpeter who played for Handel, and for two centuries it was the most reliable way to carry a pitch from place to place. The trouble was that nobody agreed on the pitch. Surviving forks and organs show A ranging from below 400 Hz to above 460 Hz depending on the city and the decade, and orchestras tended to creep sharper because a higher pitch sounds brighter.

France fixed A at 435 Hz by law in 1859, and a conference in London in 1939 recommended 440 Hz, which the International Organization for Standardization adopted as ISO 16 in 1955 and confirmed in 1975. Many orchestras still tune slightly higher, to 442 or 443 Hz, while baroque ensembles often use 415 Hz, roughly a semitone lower.

Electronic tone generators arrived with the vacuum tube. One of the first successful products of Hewlett-Packard, the HP 200A audio oscillator of 1939, was a precision sine generator, and Walt Disney's studio bought eight of an improved model to test the sound systems for the film Fantasia.

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