Frequency audio

Binaural, monaural, isochronic

Binaural beats (Oster, 1973): two close pure tones, one per ear. The brainstem (superior olivary complex) hears the difference. Headphones are not a suggestion — without stereo isolation there is no binaural beat, only a mix. Typical carriers sit between 100 and 400 Hz. The beat is |fL − fR|, usually 1–30 Hz.

Monaural beats mix the two tones before they hit the air — they work on speakers, and feel more like acoustic roughness than a ‘hidden’ pulse. Isochronic tones are a single tone, amplitude-gated at the beat frequency. They do not need headphones and often feel stronger. For a desk-focus product, isochronic is usually the better default. For a night journey, binaural plus brown noise is the classic.

Does the EEG lock to the beat? Sometimes, modestly, not like a metronome in every skull. Anxiety and some sleep-onset studies are the least embarrassing literature. ‘Gamma genius’ and ‘manifest at 528’ are not. Sell a felt experience and a plausible brain-state neighborhood, not a hospital-grade protocol.

Bands, used like a grown-up

Delta 0.5–4: deep sleep. End there; do not start a session at 2 Hz or people feel foggy and cheated. Ramp 6 → 2 on a night track.

Theta 4–8: imagery, hypnosis, the edge of sleep. Default for inner work. 6 Hz is a workhorse.

Alpha 8–13: eyes-closed rest, the pause. Daytime calm.

Beta 13–30: desk attention. Keep it short and quiet. 16 is plenty.

Gamma 40-ish: some meditation research, easy to make ugly. Isochronic often beats binaural here because a 40 Hz difference on a 200 Hz carrier is a stretch to hear as a beat.

Schumann 7.83: a real electromagnetic resonance of the Earth–ionosphere cavity. An audio 7.83 Hz beat is just high-theta. You may use it as a taste. Do not claim you are piping in the planet.

The rest of the shelf

Solfeggio (174, 396, 417, 528, 639, 741, 852, 963) is a modern esoteric set, not a recovered Gregorian tuning. 432 versus 440 is a preference. Pink and brown noise have a more respectable sleep literature than most beats — especially pink noise timed near slow oscillations. If you can only have one layer under a night voice, brown noise at low volume often wins.

Mix discipline: one carrier, one beat (optionally ramped), optional noise, optional very quiet solfeggio. Three beating layers is a headache, not a product. Volume of the bed should sit under the voice like a floor, not a competitor. Sine waves are loud; 0.1–0.16 on a master is typical.