Brainwave Session Planner

A binaural beat is an auditory illusion: feed two slightly different pure tones, one to each ear, and the brain perceives a third "beating" tone at the difference frequency — even though no physical signal at that frequency exists. This tool functions as a binaural beat sequencer and brainwave entrainment planner: it strings several beat frequencies together into a timed sequence, so the perceived beat moves from one brainwave band to another over the course of a session instead of holding a single value.

The math

f_{perceived beat} = | f_left − f_right |

This planner sends f_L = base (carrier) to the left channel and f_R = base + beat to the right, using Web Audio's ChannelMergerNode to keep the two signals in separate physical channels. Each segment you add sets the beat value; when one segment ends, the planner uses linearRampToValueAtTime to glide the right oscillator from the old beat to the new one over a few seconds, so transitions are smooth rather than abrupt. All timing is anchored to audioCtx.currentTime — the audio clock — rather than wall-clock timers, so segment boundaries stay accurate even if the tab is briefly throttled.

EEG brainwave bands

Each segment is labelled with a standard EEG band based on its beat frequency:

• Delta (δ): 0.5–4 Hz — deep dreamless sleep, healing, unconscious processing.
• Theta (θ): 4–8 Hz — deep meditation, REM dreaming, creative flow, hypnagogic states.
• Alpha (α): 8–13 Hz — relaxed alertness, calm awareness, light meditation.
• Beta (β): 13–30 Hz — active thinking, focused attention, problem-solving.
• Gamma (γ): 30–40 Hz — peak cognition, sensory integration, heightened perception (this tool caps the beat at 40 Hz).

Does brainwave entrainment actually work?

The hypothesis behind binaural, monaural, and isochronic beats is the frequency-following response (FFR): the idea that neural oscillations may partially track a perceived beat frequency, as measured by EEG. Lab studies do reliably show small, statistically detectable EEG power shifts that follow the beat — that part is reasonably well supported. What is far less clear is whether those shifts produce meaningful real-world outcomes. Studies on relaxation, focus, mood, and sleep report effects that are generally small, inconsistent across people, and not clinically established, hampered by small samples and weak placebo controls (it is hard to blind someone to a pulsing sound). The honest summary: FFR is a real auditory-neuroscience phenomenon; its practical benefits are plausible but unproven. Use this planner for relaxation or experimentation — never as a treatment for any condition or a substitute for professional medical care.

Why sequence the bands?

The appeal of a sequence is the "journey" framing. A wind-down session, for example, starts in beta (alert), then descends through alpha and theta into delta, mirroring the natural progression toward sleep; a focus ramp moves from a relaxed alpha into an attentive beta. Whether the brain actually follows these transitions is exactly the open question above, so treat the presets as comfortable listening structures rather than guaranteed state changes. You are always free to build your own ordering — the segments are just a list you can add to, reorder, and time however you like.

How to use this tool

1. Put on stereo headphones. The binaural effect requires physical channel separation.
2. Load a preset sequence (Wind-down, Focus ramp, Deep meditation, or Power nap) or build your own by adding segments.
3. For each segment, pick a brainwave band or type an exact beat frequency (0.5–40 Hz) and set its duration in minutes; use the arrows to reorder and ✕ to remove.
4. Set the carrier frequency (default 200 Hz) and a comfortable volume, then press Play.
5. Watch the "Now playing" panel for the current segment, band, and countdown. The audio fades out gently at the end of the session.