双耳节拍生成器

What a binaural beat actually is

A binaural beat is not a sound in the recording — it is an illusion your brain creates. When one ear hears a pure tone at, say, 200 Hz and the other ear hears 210 Hz, the brain perceives a third, phantom pulsing at the difference: 10 Hz. That 10 Hz "beat" exists nowhere in the audio itself; it is constructed where the two signals meet in the auditory pathway. This tool generates exactly that — two sine-wave oscillators, one routed to your left ear and one to your right, at frequencies you control. The phantom beat is the gap between them.

Why headphones are mandatory, not optional

This is the single most important thing to understand. The effect depends on each ear receiving a different frequency in isolation. Loudspeakers let the two tones mix in the air before they reach you, so both ears hear the same blended sound and the illusion collapses into an ordinary audible warble. Only stereo headphones or earbuds keep the channels separate. The tool routes the left oscillator strictly to channel 0 and the right to channel 1 through a channel merger, so without headphones there is genuinely nothing to perceive.

The carrier and the beat: two separate dials

You set two independent frequencies. The carrier (100–400 Hz) is the base pitch both ears hear — it determines how high or low the tone sounds. The beat (1–40 Hz) is the difference added to the right ear, and it determines the phantom pulse. So a 200 Hz carrier with a 10 Hz beat sends 200 Hz left and 210 Hz right, and you perceive a 10 Hz throb. Changing the carrier moves the audible pitch without changing the beat; changing the beat moves the phantom pulse without changing the pitch. The display always shows you all three numbers: left ear, right ear, and the resulting beat.

The brainwave presets explained

The five presets map the beat frequency onto the named bands of human EEG brainwave activity:

The premise behind binaural beats is "entrainment" — the idea that exposing the brain to a beat frequency may gently nudge its own rhythms toward that band. It is fair to be clear-eyed here: the scientific evidence for strong entrainment effects is mixed and far from settled. Many people nonetheless find the steady, gentle tones genuinely useful for relaxation and concentration, much like ambient noise. Treat the presets as a starting point for how a session feels, not as a medical claim.

A worked example

Click the Alpha preset: the carrier sets to 200 Hz and the beat to 10 Hz, so the display reads left 200, right 210, beat 10. Press Play and the volume fades in over half a second (a deliberate ramp to avoid a jarring click). The waveform visualizer shows the combined signal, and a timer counts your session length. Now drag the beat slider down to 6 Hz while it plays — the right-ear tone slides smoothly to 206 Hz in real time, and you have moved from Alpha into the Theta range without stopping the audio. Lower the carrier to 150 Hz and the whole tone deepens while the 6 Hz pulse stays put.

Practical tips and safe listening

• Start the volume low. Pure sine tones can feel louder than music at the same setting; begin around the default and raise it slowly.
• Confirm stereo separation. If the beat sensation is faint or absent, check that your headphones are seated correctly and not in mono mode.
• Match the beat to your goal. Lower beats (Delta, Theta) suit winding down and sleep; higher beats (Beta, Gamma) suit study and focus.
• Sessions, not marathons. Use it for a focused block — a study sprint, a meditation, a pre-sleep routine — rather than all day.
• Safety note. If you have epilepsy or a seizure history, or you experience dizziness, stop and consult a professional; rhythmic audio affects people differently.

Privacy

The tones are synthesized live in your browser with the Web Audio API. No audio file is downloaded or streamed, nothing is recorded, and nothing leaves your device — the generator runs entirely offline once the page has loaded.