tickBinaural method
Implementation
void tickBinaural(double beatHz, double dt) {
if (beatHz <= 0) return;
_binauralBeat = beatHz;
_binauralPhase += dt * beatHz * 2 * pi * 0.25; // lento, perceptual
_binauralPhase %= (2 * pi);
notifyListeners();
}