How to use the tone generator
- Set the volume low, then press Play.
- Change the frequency while it plays: drag the slider, type a number, or use the buttons. ÷2 and ×2 move a whole octave.
- Choose the wave shape, and whether it plays in the left ear, the right ear or both.
On a computer, the up and down arrow keys move the frequency by 1 Hz, and with Shift by a semitone. Sweep 20 Hz to 20 kHz glides through the whole range of hearing in 20 seconds.
Notes and tuning
Under the frequency, the tone generator names the nearest musical note and how far off it is in cents, hundredths of a semitone. It uses the standard tuning pitch, with the A above middle C at 440 Hz. The buttons below the controls play common reference notes and the six strings of a guitar in standard tuning, from E2 at 82.41 Hz to E4 at 329.63 Hz, so you can tune by ear.
The four wave shapes
- Sine is a pure tone: one frequency and nothing else. Use it for testing and measuring.
- Square adds the odd harmonics, three, five and seven times the frequency and up, which makes it buzzy and hollow, like an old game console.
- Triangle has the same odd harmonics but much weaker, so it sounds softer, close to a sine.
- Sawtooth has every harmonic and sounds bright and brassy.
Square and sawtooth waves sound much louder than a sine at the same setting, so the generator plays them at half the level.
What people use it for
- Testing speakers and headphones: sweep the range and listen for rattles, buzzing or a band where the sound drops away.
- Finding a rattle: hold the frequency where something buzzes and move around the room to find it.
- Tuning an instrument by ear, from the note buttons.
- Science and music lessons: hearing octaves, beats between two close frequencies, or how wave shape changes the sound.
High frequencies
Hearing reaches about 20,000 Hz at best, and the top of it fades with age, so many adults hear nothing at the highest settings. Speakers also roll off at the very top. This is a tone generator, not a hearing test: if you are worried about your hearing, see an audiologist.
Keep it safe
Pure tones at high volume are unpleasant and can harm hearing, especially through headphones, and very high or very low tones can damage small speakers. Start low and turn up gradually.
To check left and right, use the sound test. For the low end, use the bass test.