Free tool · runs in your browser
Tone generator 20 Hz to 20 kHz
Play a steady tone at any frequency. Drag the slider, type a number or pick a preset, and choose the waveform. The tone is made on this page, so there is nothing to download.
Start with the volume low. Very high and very low tones can be loud even when you barely hear them.
Frequencies worth trying
- 20 to 60 Hz: deep bass. Only subwoofers, larger speakers and good headphones play it.
- 100 to 250 Hz: the body of bass and kick drums. Small speakers start to work here.
- 440 Hz: the note A, the reference for tuning instruments.
- 1 to 4 kHz: where hearing is most sensitive and where speech is easiest to understand.
- 10 kHz and above: the top of the range. Where you stop hearing it depends on your age and your speakers.
Find a rattle or a weak spot
Set the waveform to sine, start the tone at a low volume and move the slider slowly through the bass. A loose panel or shelf buzzes at one narrow frequency. A sudden dip or peak in loudness shows where the speaker or the room is uneven.
For a full run from bottom to top with a left and right check, use the sound test. To shape those frequencies for one app on a Mac, see the per-app equalizer.
SoundDial for Mac
You found the frequencies. Now shape them per app.
SoundDial gives each app on your Mac its own volume slider, mute and ten-band equalizer, so you can add bass to the music without changing the call. Try it here with three example apps.
Interactive demo with example sounds, running in your browser. The real SoundDial controls the apps on your Mac.
FAQ
What is a tone generator used for?
It plays one steady frequency. People use it to check how low a subwoofer or how high a speaker goes, to find the frequency where a shelf or a car door rattles, to tune an instrument against a reference note, and to compare two pairs of headphones.
What is the difference between sine, square, sawtooth and triangle?
A sine wave is a pure tone with a single frequency. Square and sawtooth waves add many higher overtones on top, so they sound buzzy and seem louder; this page plays them at half the level for that reason. A triangle wave has only a few weak overtones and sounds like a slightly brighter sine.
Why can I not hear 20 Hz or 15 kHz?
Laptop, phone and small desktop speakers cannot move enough air for the deepest notes, so very low tones are silent on them even though they are playing. At the top, hearing for high frequencies fades with age, and many adults no longer hear tones above about 15 kHz. Do not turn the volume up to find a tone you cannot hear.
Is 440 Hz the note A?
Yes. 440 Hz is the A above middle C (A4) and the usual reference pitch for tuning instruments. Each octave doubles the frequency, so 220 Hz and 880 Hz are also A.
Can a test tone damage speakers or hearing?
A loud steady tone can do both, more easily than music at the same volume setting. Start low, raise the volume slowly, and be extra careful with headphones and with very high or very low frequencies that you barely hear.