Play a tone that glides from one frequency to another over a set time. Choose the waveform and a linear or logarithmic sweep. Useful for tests and effects.
A logarithmic sweep matches how we perceive pitch, so it sounds more even across the range; a linear sweep moves faster through the highs. Generated live with the Web Audio API. Keep the volume moderate, especially for high frequencies.
Sweeps (also called chirps or glides) are used to test speakers and headphones for buzzes or dead spots, to train your ear to recognise pitches, to find room resonances, and as a sound-design effect.
A linear sweep changes by equal frequency steps, so it races through the high end quickly. A logarithmic sweep changes by equal musical intervals, matching human hearing, so it sounds smooth and even across the whole range.
High frequencies and square or sawtooth waves can be harsh and surprisingly loud. Start quiet, especially with headphones, and raise it carefully.