Tone Generator

Generate pure test tones in your browser

A tone generator produces a single, steady pitch at a frequency you choose. This one lets you sweep from a deep 20 Hz rumble up to a piercing 5,000 Hz with the slider, or type any exact frequency in the box for precise work. The large readout shows the current frequency in hertz so you always know what you are hearing. Adjust the frequency, waveform and volume live while the tone is playing — the sound updates instantly without clicks or gaps.

Tone generators are handy in many situations. Musicians use a reference tone such as A4 at 440 Hz to tune by ear or to check another tuner. Audio enthusiasts test the frequency response of speakers and headphones, hunt for buzzes and rattles, or verify channel balance. Teachers and students use steady tones for ear training and to explore how pitch relates to frequency. You can even gauge the rough upper limit of your own hearing by slowly raising the frequency.

Choosing a waveform

The waveform determines the tone's timbre — its character — while the frequency sets the pitch. A sine wave is the purest tone, containing a single frequency with no overtones, which makes it ideal for tuning and hearing tests. A square wave sounds hollow and buzzy because it contains only odd harmonics. A sawtooth wave is the brightest and harshest, packed with both odd and even harmonics, and is a staple of synthesisers. A triangle wave is softer than a square but richer than a sine. Switching between them at the same frequency is a great way to hear how harmonics shape a sound.

Listen safely

Pure tones can be deceptively loud and fatiguing, so start with the volume low and increase it slowly, particularly with headphones. Very high or very low frequencies may be hard to hear yet still drive your speakers hard, so be gentle with the volume there too. Everything is synthesised locally by the Web Audio API in your browser, which means the tool works offline and never records or transmits any audio.