Online Tone Generator from 20 Hz all the way to 20 kHz

Getting a tone out of it

There’s honestly not much to learn. I’d start with your volume down low, because a pure tone always seems twice as loud as you expected (square and sawtooth are worse), then type the frequency you want into the box or drag the slider until the readout says what you need. The slider’s a bit unusual, and on purpose: its lower half crawls from 20 to 1,000 Hz in small steps, since that’s where most of the fiddly speaker work happens, and the upper half races on up to 20 kHz.

Pick one of the four wave buttons, press Start, and the ring around the button counts the time down. If you move the slider while it’s going, the pitch slides smoothly over instead of jumping, which is oddly satisfying, and the scope above draws whatever shape is heading to your speaker along with the current frequency in its corner.

All of this happens inside the browser tab using the Web Audio API. Nothing’s downloaded, you don’t need an account, and once the page has loaded you could pull the network cable and it’d keep humming away. So think of it as a pure tone generator, an hz generator and a little scope rolled into one box.

What the four wave shapes sound like

If you only ever use one, make it the sine. A sine wave carries a single frequency and nothing else, which makes it the fairest test you can give a speaker, since every buzz or fizz you hear has to be coming from the hardware. The square wave is the opposite case: it piles a whole ladder of odd harmonics on top of the note, and that’s why 100 Hz as a square sounds so much brighter and louder than 100 Hz as a sine. I’ve trimmed the square’s level a little so it doesn’t take your head off.

Frequencies people actually use

Pitch is counted in hertz, cycles per second, and every time you double the number you land an octave higher, which is why 220, 440 and 880 all come out as an A.

Where does your hearing stop?

Half the people who find a frequency generator are really just curious how high they can still hear, and I get it, it’s a fun thing to try. Set it to sine, keep the volume low, start somewhere around 8,000 Hz and creep the slider upwards a little at a time until the tone just sort of evaporates. Teenagers often get to 17 kHz and beyond, while lots of perfectly normal adults lose it somewhere in the 12 to 16 kHz zone. Bear in mind that a cheap pair of earbuds might quit before your ears do, and this is a curiosity rather than a hearing test; an audiologist is who you’d see if you’re actually worried.

Tracking down a rattle

You know the buzz that turns up on one song and vanishes on the next? That’s almost always something resonating at a single pitch, maybe a loose screw, a trim panel in the car door, or a cable lying against a speaker cone. With a sine wave at a moderate level, start low around 40 Hz and drag upwards slowly. The moment the buzz joins in, write the number down and press lightly on the nearby panels one by one, and whichever one makes it go quiet is the bit that wants tightening or a scrap of foam.

Can it clear a wet speaker?

It runs on the same engine as the speaker cleaner, so yes, sort of. When the standard 165 Hz water eject hasn’t quite done it, you can try a handful of sine settings between 150 and 200 Hz for one to three rounds. Dust responds better to something that moves, though, so for a dusty grille I’d go back to the homepage and use Dust Sweep. High tones are useless for this job, by the way, because the cone barely moves at those frequencies and can’t push the water anywhere.

Be kind to your ears

A steady tone gets tiring quicker than music does, square and sawtooth pack more energy than a sine at the same setting, and very high pitches can be properly unpleasant even when they don’t seem loud at all. So creep the volume up rather than jumping, and don’t sit in headphones with this for ages. The CDC’s page on noise and hearing loss explains how level and time add up together. You only need the tone loud enough to hear it clearly, nothing more.

Why it sounds different on every device

What comes out depends heavily on what’s playing it. A phone speaker is tiny, so below about 150 Hz things get faint fast, and at 40 Hz you might hear almost nothing even though the scope shows the wave is plainly there. Laptops reach a bit lower, headphones lower again, and a decent set of desk speakers or a soundbar will happily cover the whole range of this audio frequency generator. Bargain earbuds sometimes run out of steam above 12 or 14 kHz. If you’re comparing devices, leave the frequency and wave alone and only swap the device, otherwise you’re testing your settings rather than the hardware.

Tone generator or speaker test?

Reach for this tone generator online when you want one exact pitch held for as long as you like. If you’d rather have a quick once-over of both channels plus an automatic sweep from 20 Hz to 20 kHz, the speaker test does that in about a minute.