This tone generator plays a steady tone at any frequency from 1 Hz to 20,000 Hz, the full range of human hearing and then some. Use it as a sine wave generator for clean test tones, or switch to square, triangle or sawtooth waves when you want harmonics. You can send the tone to the left, right or both channels, add a second tone to hear beats, pick a musical note, set a stop timer and save any tone as a WAV file. It runs in Chrome, Edge, Firefox and Safari on Windows, Mac, ChromeOS, Linux, iPhone and Android, through speakers, headphones or a phone's own speaker.
How to use the tone generator
- Turn your system volume down to about a third before you start. Test tones are steadier and more piercing than music.
- Drag the slider, type a frequency in the box, or press a preset. The slider is logarithmic, so every octave takes the same width.
- Press Play tone. Change the frequency while it plays; it glides without clicks.
- Fine tune with the −0.1 to +10 keys, or jump an octave with ÷2 and ×2.
- Pick a note and octave to play its exact pitch. Change A4 tuning if your instrument is not tuned to 440 Hz.
- Set Stop after if you want the tone to end on its own, and press Copy link to share the exact settings.
Click any control in the tool, then use the keyboard: the left and right arrows move 1 Hz (hold Shift for 10 Hz, Alt or Option for 0.1 Hz), the up and down arrows move a semitone, Page Up and Page Down move an octave, and Space starts and stops the tone.
What the readouts mean
| Readout | What it tells you | Example at 440 Hz |
|---|---|---|
| Frequency | Cycles per second, to 0.01 Hz | 440.00 Hz |
| Note | The nearest note and how far off it is, in cents (100 cents make a semitone) | A4, exact note |
| Period | How long one cycle lasts | 2.273 ms |
| Wavelength | How long one cycle is in air at 20 °C, where sound travels 343 metres a second | 78.0 cm |
| Level | The peak level sent to your system, in dB below full scale (dBFS), and the RMS level | Peak −18.2 dBFS at 35% volume |
| Beat | The difference between the two tones when the second tone is on | 4.0 Hz for 440 and 444 Hz |
The level is digital, before your system volume and speakers. A square wave at the same setting is about 3 dB louder than a sine because its RMS level is higher, which the RMS figure shows.
Choosing a waveform
| Wave | What it contains | Sounds like | Good for |
|---|---|---|---|
| Sine | The fundamental only | A pure, smooth whistle | Hearing checks, speaker and room tests, reference tones |
| Square | Odd harmonics at 1/3, 1/5, 1/7 of the level | Hollow and buzzy, like an old game console | Spotting distortion, checking amplifier clipping |
| Triangle | Odd harmonics that fall off faster | Soft, between a sine and a square | Gentle test tones, simple synth sounds |
| Sawtooth | Every harmonic, falling at 1/n | Bright and brassy | Filters, EQ and synth tests |
Every wave is made without aliasing, so a 10 kHz square wave holds only the harmonics below 20 kHz and no false tones fold back into the audible range.
What a tone generator is used for
- Speaker and headphone checks. Play 100 Hz, 1 kHz and 10 kHz through Left and Right to hear each driver. For a channel check with voice prompts, use the stereo test.
- Finding a rattle. Step through low frequencies slowly; when something in the room or the speaker cabinet buzzes, note the frequency and tighten or pad that part. The bass test has ready made low tones for this.
- Your hearing range. Raise the frequency until the tone fades. The dedicated hearing frequency test does this step by step for each ear.
- Tuning. A4 is 440 Hz in standard tuning, and any note can be played with the note picker. To check what pitch you are singing or playing, use the pitch detector.
- Checking a microphone or analyzer. Play a known tone into a mic and see that a spectrum analyzer shows the peak where it should be.
- Masking a sound. A single tone is a poor mask. For a steady sound that covers voices or traffic, use the noise generator instead.
Two tones and beats
Turn on Second tone for beats and set an offset, for example 4 Hz. With Both ears, the two tones mix in the air and in your speakers, so the sound swells and fades 4 times a second. That is an acoustic beat, and musicians use it to tune: the beat slows down as two strings come into tune and stops when they match.
With One per ear, tone 1 goes to the left and tone 2 to the right. Each ear hears a steady tone, but with headphones many people still hear a slow wobble, because the brain compares the two ears. This is called a binaural beat. Some apps sell binaural beats for focus or relaxation; studies of those claims disagree, and this page makes no such claim.
You hear nothing, or only one side
- Output set to one side. Check that Output is on Both. With One per ear, each tone plays in one ear only.
- The frequency is outside what the speaker can play. Laptop speakers produce little below about 150 Hz and phone speakers little below about 300 Hz. Try 1 kHz first.
- The tone is above your hearing. Above about 15 kHz many adults hear nothing. Lower the frequency before raising the volume.
- iPhone in Silent mode. Some browsers keep page audio quiet in Silent mode. Turn it off with the switch or Action button on the side.
- Wrong output device. Headphones or a Bluetooth speaker may still be connected. On Windows, pick the output in Settings, then System, then Sound. On a Mac, use System Settings, then Sound, then Output.
- The tab is muted. Right click the tab in Chrome or Edge and check that the site is not muted.
If no sound plays anywhere on the computer, follow the guide for no sound on computer, and for one dead speaker see speakers not working.
The tone buzzes, rattles or crackles
A clean sine wave should sound smooth. If it buzzes, work through these:
- Too loud for the speaker. Low tones make the cone move furthest. Lower the volume until the buzz stops; small speakers often rattle below 100 Hz at any real volume.
- Something loose nearby. Hold the speaker grille, a shelf or the laptop lid. If the buzz changes, that part is resonating, not the speaker.
- A square or sawtooth wave. Their harmonics sound buzzy by design. Switch to Sine before judging the speaker.
- Bluetooth. Wireless links compress the sound. A plain tone through a weak connection can warble. Test with a cable to compare.
- A damaged driver. If a sine buzzes at moderate volume at every frequency, the speaker cone or coil is likely damaged.
Saving a tone as a WAV file
The Save panel makes a WAV file in your browser from the current wave, frequency, output, second tone and volume. Files are 16 bit PCM at 44.1 or 48 kHz, mono unless you chose one side or one tone per ear, with 10 ms fades at each end. Lengths run from 1 second to 5 minutes; a 10 second mono file is about 0.9 MB. The file name records the settings, for example tone-440Hz-sine-10s.wav.
What a tone generator cannot measure
The tool knows the exact digital frequency and level it sends, but not how loud the sound is in the room. That depends on your system volume, your speakers and your distance from them. To measure the sound level, use a sound level meter near your ears. Frequency accuracy depends on your device's audio clock, which is normally within a few hundredths of a hertz at 440 Hz. The tool stops at 20 kHz, the usual top of human hearing; above that, most sound cards and speakers roll off and almost nobody can hear a tone at a safe level. This is a test tool, not a medical hearing test.
Tone generator questions
What frequency should I use to test speakers?
No single tone tells you everything. A 1 kHz tone is the usual reference for checking that sound comes out at all, 100 Hz checks the bass driver, and 10 kHz checks the tweeter. To hear the whole range in one go, run a frequency sweep from 20 Hz to 20 kHz.
What frequency is mains hum?
Mains hum sits at the frequency of your power supply: 50 Hz in the UK, Europe, most of Asia, Africa and Australia, and 60 Hz in North America. A buzzing hum often has a strong part at twice that, 100 or 120 Hz. Play those presets next to the hum to confirm it.
Can a frequency generator be used for healing?
There is no good evidence that tones such as 432 Hz or 528 Hz heal the body, and this page makes no health claims. The generator plays those frequencies like any other. If you hear ringing in your ears, an audiologist can match its pitch with a tone like this as part of a proper hearing check.
Why can I not hear very high tones?
The top of human hearing drops with age. Teenagers often hear up to 17 to 19 kHz, while many adults over 40 stop somewhere between 12 and 15 kHz. Small laptop and phone speakers also fall away above about 15 kHz, so try headphones before blaming your ears.
Is a tone generator safe for my speakers and ears?
Yes, at sensible levels. Start at a low volume and raise it slowly. Long, loud high tones can overheat a tweeter, and loud tones below a speaker's range make the cone travel too far and buzz. Very high tones can be loud without sounding loud, so never turn the volume up just because you cannot hear one.
How do I download a tone as an audio file?
Set the frequency, wave, output and volume, type a length of 1 to 300 seconds in the Save panel and press Download WAV. The file is made in your browser as 16 bit WAV at 44.1 or 48 kHz, with short fades so it starts and ends without a click.