Frequency Generator

The frequency generator covers 20 Hz to 20000 Hz, which is the range most people can hear, and moves in steps of one hertz anywhere inside it.

The generator offers sine, square, triangle and sawtooth, the four waveforms a browser oscillator can produce. Noise is not among them, because noise needs a different kind of source.

A steady tone is a reference anyone can check against. It reveals a rattling speaker, a mismatch between two headphones, and the frequency at which a room starts to boom.

The tone starts at 25 percent volume and can be raised to full. The generator caps the output gain below full scale so a laptop speaker distorts less at the top of the range.

The note readout names the closest equal-tempered note to the frequency you set, using A4 at 440 Hz as the reference, so 440 Hz reads A4 and 220 Hz reads A3.

A test tone is safe at a low level and less so as the volume rises, because a sustained tone at full volume can damage hearing. The tone plays through the browser and cannot be recorded or exported, so a quiet level and a short test are the safer habit.

Browsers allow audio only after a user gesture, so the generator opens its audio context on the play press itself. If the tone is still silent, check the system output and the volume control on the page.

Credits and sign-in are not involved at all: the tone is produced in the browser, so nothing leaves the page while it is playing.

Frequency Generator runs in the browser and draws zero credits.