Detectors

Browser-side EEG processing hooks — React refs, zero re-renders. Read .current in your requestAnimationFrame loop.


import { useBandPowers, useBlink, useFocus, useRelax } from "../../hooks/detectors";

`useBandPowers(eegData, config?)`

Foundation layer. Single FFT instance, averaged spectral band powers.

Field	Type	Description
`absolute`	`BandPowers`	Absolute power per band (µV²/Hz) — Delta, Theta, Alpha, Beta, Gamma
`relative`	`BandPowers`	Normalized to sum = 1
`totalPower`	`number`	Sum across all bands
`dominantFrequency`	`number`	Peak PSD bin (Hz)

Config: { updateHz?, channels?, smoothing? }

`useBlink(eegData, config?)`

Ocular artifact detector. Amplitude-threshold state machine on frontal channels (Fp1/Fp2).

Field	Type	Description
`blinked`	`boolean`	`true` for exactly one poll cycle per blink
`count`	`number`	Cumulative blink count
`amplitude`	`number`	Current peak-to-peak µV
`lastBlinkTime`	`number`	Epoch ms of last confirmed blink

Config: { channels?, threshold?, windowMs?, minDurationMs?, maxDurationMs?, refractoryMs?, pollHz? }

`useFocus(eegData, config?)`

Cortical engagement index — (Beta + Gamma) / (Alpha + Theta + Delta).

Field	Type	Description
`focus`	`number`	0 (relaxed) – 1 (highly focused), smoothed
`raw`	`number`	Unsmoothed, uncalibrated ratio
`calibrated`	`boolean`	Whether baseline has been captured

Config: { channels?, updateHz?, smoothing?, scaleDivisor? }

Returns: { state, calibrate(), resetCalibration(), calibrating }

`useRelax(eegData, config?)`

Alpha-dominance + theta-beta ratio composite relaxation index.

Field	Type	Description
`relaxation`	`number`	0 (alert) – 1 (deeply relaxed), smoothed
`alphaRelative`	`number`	Alpha / total power (0–1)
`thetaBetaRatio`	`number`	θ / β raw ratio
`calibrated`	`boolean`	Whether baseline has been captured

Config: { channels?, updateHz?, smoothing?, alphaWeight?, tbrCeiling? }

Returns: { state, calibrate(), resetCalibration(), calibrating }

Usage Pattern

All detectors use the same ref-based pattern for zero-rerender reads:


const { state: focus } = useFocus(eegData);
 
useEffect(() => {
  let raf: number;
  function loop() {
    const f = focus.current.focus; // read directly, no re-render
    // use f to drive animation, game logic, etc.
    raf = requestAnimationFrame(loop);
  }
  raf = requestAnimationFrame(loop);
  return () => cancelAnimationFrame(raf);
}, []);