Tone Generator
Clean test tones from 20 Hz to 20 kHz — sine, square, triangle, sawtooth.
A test-tone generator that synthesises the sound live with the Web Audio API — no audio files, no downloads, nothing uploaded. The four waveforms cover the standard test palette: a pure sine for frequency checks, and the harmonic-rich triangle, square and sawtooth for finding rattles, resonances and distortion.
Start at low volume, especially with headphones and high frequencies.
How to use
- Type a frequency or drag the slider (it is logarithmic, like hearing itself).
- Press Play. Change the waveform, volume and stereo balance while it runs — everything updates live.
- Use the preset buttons for the classic checkpoints: 440 Hz (concert A), 1 kHz (audio reference), and the high-frequency steps for a rough hearing-range check.
About this tool
Typical jobs: checking whether both earbuds work (balance slider), finding the frequency of a room hum or a coil whine, setting up speakers, tuning by ear against a reference pitch, and exploring the top of your own hearing range.
Hearing changes with age and headphone quality; treat any at-home frequency check as a rough indication, never a medical result.
How it works
A tone is a pressure wave repeating at a set frequency, measured in hertz (cycles per second). The generator synthesises the waveform mathematically in real time: a sine contains only the fundamental, while triangle, square and sawtooth waves add harmonic overtones in fixed recipes — which is why they sound progressively brighter at the same pitch.
Human hearing spans roughly 20 Hz to 20 kHz in childhood and narrows with age, mostly from the top. It is also logarithmic: each doubling of frequency is one octave and feels like the same step anywhere in the range. The slider follows that law, and the balance control uses the stereo panner to place the tone anywhere between the left and right channels.
Worked examples
Which earbud died?: Play 440 Hz, then drag Balance fully left, then fully right. If one side is silent or much quieter at the same setting, the problem is the earbud or its cable — not the song, not your ears.
Hunting a room hum: Mains hum is 50 Hz (or 60 Hz) plus harmonics at 100/120 and 150/180 Hz. Sweep slowly through 40–200 Hz; when the generated tone matches the mystery hum and seems to swell or beat against it, you have found its frequency — and usually its source.
Quick reference
| Frequency | Landmark |
|---|---|
| 20 Hz | Bottom of nominal human hearing — felt more than heard |
| 55 Hz | A1, the lowest A on a piano is 27.5 Hz (A0) |
| 440 Hz | A4 — concert pitch, the tuning reference |
| 1,000 Hz | Standard audio test reference |
| 4,000 Hz | Presence range — where hearing is most sensitive |
| 10,000 Hz | Most adults over 40 no longer hear this |
| 16,000–20,000 Hz | Top of the range; many speakers cannot reproduce it |
Frequently asked questions
Why does the slider move in uneven steps?
Hearing is logarithmic: the jump from 100 Hz to 200 Hz feels like the jump from 1 kHz to 2 kHz. The slider follows the same law, so low frequencies get fine control and the whole 20 Hz–20 kHz range fits on one bar.
Sine, square, triangle, sawtooth — what is the difference?
A sine is a single pure frequency. The others add harmonics: a triangle is a softened, flute-like version; a square sounds hollow and strong on odd harmonics; a sawtooth is the brightest and buzziest. Harmonic tones are far easier to hear at very low frequencies than a pure sine.
Can I check my hearing range with this?
Roughly. Most adults hear up to about 14–17 kHz, less with age, and many laptop speakers and earbuds cannot reproduce the extremes at all — silence at 18 kHz may be your hardware, not your ears. This is not a medical hearing test.
Is it safe for my ears and speakers?
At moderate volume, yes. Start low: high frequencies and square/sawtooth waves get harsh fast, and small speakers can be damaged by loud low-frequency tones played for a long time.
Does it work on phones?
Yes — tap Play once (browsers require a gesture before sound) and the tone runs until you stop it. Use the balance slider to check earbuds one side at a time.
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