Play a pure tone at any frequency from 20 Hz to 20 kHz, for testing speakers and headphones, finding room resonances, checking the top of your hearing, or as a reference pitch. The frequency slider is logarithmic, so equal distances are equal musical intervals instead of cramming the entire musical range into the first centimetre. Tones fade in and out over a few milliseconds rather than starting abruptly, which avoids the click that is unpleasant on headphones and hard on tweeters. Sine, square, sawtooth and triangle waveforms, output to either channel or both, the nearest note name with its deviation in cents, and sweeps between two frequencies. Generated live by your browser — nothing is downloaded or uploaded.
This tool does not use any data storage or network traffic.
440.00 Hz
A4 · exact
Note names use the A4 = 440 Hz reference.
Fine tune
Waveform
Output
Reference frequencies
A logarithmic sweep moves at a constant musical rate — it spends as long crossing 20–40 Hz as it does crossing 10–20 kHz. A linear sweep moves at a constant number of Hz per second, so it races through the bass and crawls through the treble.
Nothing leaves your browser
The tone is synthesised live by your browser's audio engine. Nothing is downloaded, nothing is uploaded, and nothing is stored.