Online Tone Generator

A tone generator plays a single steady frequency. That sounds simple, and it is, but it is the basic instrument for a surprising number of jobs: checking whether a speaker actually reproduces low bass, finding the frequency at which something in a room rattles, confirming both sides of a pair of headphones work, tuning an instrument against a reference pitch, or getting a rough sense of the highest frequency you can still hear.

Frequency runs from 20 Hz to 20 kHz, the usual bounds of human hearing. The presets cover the ones people reach for most: 440 Hz is concert pitch A, 1 kHz is the standard reference for audio measurements, 60 Hz sits where mains hum lives, and 10 kHz is up in the range that fades with age. Sine gives a pure tone with no harmonics, which is what you want for testing. Square, triangle, and sawtooth add harmonics and sound progressively harsher, which is useful for hearing what a system does with a complex signal.

Every control applies to the tone while it is playing, so you can sweep the frequency slider by hand and hear the response change. Volume ramps rather than jumping, because an instant change in level is an audible click and an unpleasant one through headphones. Start quiet: sustained tones, particularly high ones, are more fatiguing than they sound. The download writes an uncompressed WAV at the length you set, faded in and out at the edges. For counting tempo rather than generating pitch, see the metronome and the BPM counter, and for converting between frequency units the frequency converter covers it.