Dual Tone Generator
Play two tones at once for binaural beats or interval tests.
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Frequency
Settings
Binaural beats need headphones: each ear has to hear only its own tone. Through speakers the two tones mix in the air and you hear a plain beating tone instead.
Audio starts on your first tap on Play, as required by your browser. Press Space to start or stop.
A dual tone generator plays two sine tones at once. Put them a few hertz apart and you hear a beat, the slow pulse where the two waves add and cancel. This two tone generator, or binaural beat generator, gives you both frequencies, a direct beat control and a mode that sends one tone to each ear.
How to use it
- Set the beat frequency directly. The slider and the number field cover 0.5 Hz to 40 Hz and move tone B relative to tone A, so the readout at the top always shows the difference between the two.
- Or set the tones yourself. Frequency A and Frequency B each have a slider, a number field and octave buttons, and the arrow keys step in fine increments while a slider has focus. Carrier tones between roughly 200 Hz and 500 Hz are the usual choice.
- Tap a preset if you want a named band: delta 3 Hz, theta 6 Hz, alpha 10 Hz, beta 15 Hz or gamma 40 Hz. Each one only sets the beat frequency.
- Switch on binaural mode to send tone A to the left ear and tone B to the right. Put headphones on first, because through speakers the two tones mix in the air before they reach you.
- Choose a waveform and a level, add a sleep timer of 15, 30 or 60 minutes if you want it to fade out on its own, then press Play or hit the space bar.
What you can use it for
Hearing interference for yourself. Two tones a few hertz apart produce a pulse you can count on a watch, which is the plainest demonstration of wave interference there is and needs no equipment beyond a speaker.
Tuning by beats. Piano tuners and string players match two pitches by listening to that pulse and slowing it down until it stops. Set one tone to your target pitch and sound your instrument against it.
Binaural beats for relaxing or falling asleep. With one tone per ear the beat is assembled in your hearing rather than in the air. Many people find it calming; the published research on the effects is mixed, so treat it as something you may enjoy.
Checking a stereo path from end to end. Two clearly different frequencies, one per channel, make a swapped, dead or quiet channel obvious the moment you press play.
Intermodulation checks. Send both tones into an amplifier or a small speaker at a fair level and listen for pitches that are neither A nor B. Sum and difference products mean something in the chain is being driven past its limit.
What the band names mean
| Band | Beat frequency | The EEG band is named after |
|---|---|---|
| Delta | 0.5 to 4 Hz | Deep, dreamless sleep in EEG recordings. |
| Theta | 4 to 8 Hz | Drowsiness and the edge of sleep. |
| Alpha | 8 to 12 Hz | Relaxed wakefulness, strongest with the eyes closed. |
| Beta | 12 to 30 Hz | Ordinary alert thinking. |
| Gamma | 30 Hz and above | Bursts recorded during attention and perception tasks. |
Accuracy and limits
The bands above describe brain waves measured with an EEG. They are not effects this page produces, and setting a 10 Hz beat does not put your brain at 10 Hz. Studies on entrainment, mood and focus are mixed and mostly small. This is not a medical device and it makes no health claims.
A binaural beat has conditions. Each ear must hear only its own tone, which rules out speakers, and the effect depends on your ears tracking the phase of the carriers, which they do well below about 1 kHz and poorly above it. Very small beat rates below 2 Hz take half a minute of listening before the pulse is obvious.
Output is not calibrated, so the decibel slider is relative to whatever your system is doing. Bluetooth headsets are the weak link here: some of them process the two channels separately or collapse them, which blurs the effect. Wired headphones are the safer choice.
Frequently asked questions
What is a binaural beat?
Two tones of slightly different frequency, one in each ear. Neither ear hears a pulse on its own, but the difference between them is registered further up the hearing system as a slow beat. That is why headphones are part of the definition.
Do binaural beats really work?
The beat is real and easy to hear. The claims around focus, sleep and anxiety are the uncertain part: the studies are small, the results disagree, and the relaxing effect of a steady quiet sound is hard to separate from the beat itself.
What carrier frequency should I use?
Something between about 200 Hz and 500 Hz is the common choice. Low carriers work because your ears follow the phase of the wave there; above roughly 1 kHz that ability fades and the beat gets harder to notice.
Do I need headphones?
For binaural mode, yes. Without headphones the two tones meet in the air and you hear an ordinary acoustic beat, which is still a useful thing to listen to but a different effect.
Can I fall asleep with it playing?
Set the sleep timer to 15, 30 or 60 minutes and it fades out and stops on its own. Keep the level low: hours of audio at a high level is bad for your ears, and sleeping in hard earbuds is bad for your ear canals.
Can I tune an instrument with two tones?
Yes, and it is more precise than matching pitch by ear. Sound your instrument against one tone and listen for the beat. The slower the pulse, the closer you are; when it disappears the two pitches are the same.
Related tools
- Online Tone Generator: one pure tone from 20 Hz to 20 kHz
- Multi Tone Generator: up to eight tones stacked into a chord
- White Noise Generator: white, pink and brown noise with a sleep timer
- Tinnitus Frequency Matcher: a guided slider that matches the pitch you hear
- Headphone Test: four checks for left, right, polarity and range