How to Use a Tone Generator — From Speaker Checks to Tuning
Checking left and right channels, finding rattles, testing a subwoofer, a tuning reference and how waveforms differ — plus how to use a tone generator safely.
Published 2026-09-26
Checking left and right channels
Switch 'Ear' between left and right while playing a sine wave around 1 kHz, and you'll know right away whether your earphones or speakers have their channels swapped. If one side is quiet, check the cable contact or the balance setting.
Finding rattles and buzzes
Slowly raise the frequency with the slider at a low volume, and you can find the frequencies at which nearby objects — the speaker cabinet, a desk, a window — rattle. Remembering those frequencies helps when you adjust damping material or where things are placed.
Subwoofers and room bass
Sine waves from 20 to 120 Hz show how low your system goes. If the same tone gets louder or almost disappears as you move around the room, that's caused by standing waves between the walls (room modes). Move your listening position around and you'll hear the difference.
A tuning reference
Play A4 at 440 Hz and tune your instrument to it. Some orchestras use a different reference such as 442 Hz — just type the value you need into the frequency field.
What changes with the waveform
| Waveform | Harmonics | Character |
|---|---|---|
| Sine | No harmonics (fundamental only) | The purest; right for hearing tests |
| Triangle | Odd harmonics falling off fast as 1/n² | Slightly brighter than sine |
| Square | Odd harmonics falling off as 1/n | A hollow 'beep' |
| Sawtooth | All integer harmonics falling off as 1/n | The brightest and harshest |
This is why you shouldn't use square or sawtooth waves to measure your low limit. Even if you can't hear the fundamental of a 30 Hz square wave, harmonics at 90 Hz and 150 Hz are audible, fooling you into thinking you 'hear' it. That's why this site's sweeps always use sine waves. In the tone generator, square and sawtooth output is lowered so perceived loudness doesn't jump when you switch waveforms.
Volume safety
- High tones can sound piercing even at a low volume, and tweeters (treble speakers) can be damaged by prolonged loud high-frequency output.
- If you leave the volume up on a frequency you can't hear, the moment you switch to one you can hear it will suddenly be loud.
- This site caps output at −6 dBFS and adds a 0.08-second fade on every start and stop to prevent click noise.
Sharing a frequency by URL
The tone generator's frequency is stored in the address. Add something like #tone&f=440 after the site address and it opens at that frequency, making it easy to share a specific sound with someone else.