Tone Generator

A tone generator that plays any frequency from 1 Hz to 22,000 Hz in the browser. Use it to check speakers and headphones, play a reference pitch or try sound experiments.

How to use

1. Type a value into "Frequency" or move the slider, or choose a note such as A4 under "Note".
2. Choose "Sine", "Square", "Sawtooth" or "Triangle" under "Waveform", keep "Volume" low and press "Play".
3. While it plays, −1 and +1 change it by 1 Hz, ÷2 and ×2 by one octave, and "Left/right balance" moves the sound to one side.
4. For a sweep, open "Sweep (glide through frequencies)", enter the start and end frequency and the duration, and press "Play sweep".

How it works

• Note names use equal temperament with A4 = 440 Hz; one octave up is × 2 and one down is ÷ 2. The nearest note and its offset in cents are shown.
• With "Play a second tone (hear beats)" on, two tones play together, and the sound swells and fades as many times per second as the two frequencies differ.
• Speakers may not play, and people may not hear, very low or very high frequencies. Loud or high tones can strain ears and speakers, so start quietly.

Questions and answers

What note is 440 Hz?

It is A4, the A above middle C. It is the usual reference pitch for tuning, and you can hear it by choosing A4 under "Note".

Can I use this as a hearing test?

No. The tool only plays sounds, and the real loudness differs between devices and headphones, so it cannot be used to judge hearing.

How do I test the frequency range of my speakers or subwoofer?

Play a sweep from 20 Hz to 20,000 Hz at a low volume. The point where the sound disappears is the limit of the device and your ears together.

What are beats?

Beats are the regular rise and fall in loudness when two tones with slightly different frequencies play together. 440 Hz and 443 Hz together swell three times per second.