Experiment. Rays are traced on the GPU. Every bounce's arrival is deposited into an impulse response, then convolved with a click. It may sound like a room, or garbage.
GPU ray grid (32×32 = 1024 rays)
Impulse response
Large empty box, long tail
Model: Fibonacci-sphere rays, specular reflection only, flat absorption, 1/r² falloff, exponential tail envelope, random-sign summation into bins. No air absorption, diffraction, or HRTF.