Generate a pure tone at any frequency from 20 Hz to 20 kHz — sine, square, triangle or sawtooth.
A tone generator produces a continuous audio signal at a frequency you choose, using the Web Audio API built into every modern browser. The signal is created by an oscillator node connected to a gain node that controls the volume, and from there it goes straight to your speakers or headphones. There is no audio file involved: the waveform is generated mathematically in real time, which is why the frequency slider responds instantly.
Four waveform shapes are available. A sine wave is the purest tone — a single frequency with no harmonics, the kind of signal a tuning fork produces. A square wave adds all odd harmonics at decreasing amplitude, giving it a hollow, buzzy character. A triangle wave also contains only odd harmonics but they fall off much faster, producing a softer sound. A sawtooth wave includes all harmonics, both even and odd, and sounds the brightest and most aggressive of the four.
Practical uses include testing speakers and headphones for dead spots or distortion, checking the frequency range of a sound system, tuning instruments by ear against a reference pitch, and generating a steady tone for audio calibration. The volume control is important: frequencies near the extremes of human hearing — below 50 Hz or above 15 kHz — need more volume to be perceived, and high volume at any frequency can damage hearing. Start quiet and increase gradually.
Sine: y = sin(2π × f × t). Square: y = sign(sin(2π × f × t)). Triangle: y = (2/π) × arcsin(sin(2π × f × t)). Sawtooth: y = 2 × (f × t − ⌊f × t + ½⌋). All at amplitude A controlled by the volume slider.
At high volume, especially at extreme frequencies, any speaker can be damaged. Start at low volume and increase carefully. Sub-bass frequencies (under 40 Hz) are particularly risky for small speakers.
The browser may require a user gesture to start audio — click the Play button. Also check the volume slider, your system volume, and that the right audio output is selected.
Concert pitch A4, the standard tuning reference for most Western music. Orchestras tune to this frequency, and most tuners default to it.
Most people cannot hear below 20 Hz, and most consumer speakers cannot reproduce it. You may feel it as a vibration rather than hear it as a pitch.
The oscillator runs in the Web Audio API on your device. No audio data is generated as a file, transmitted or stored.
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