Each pulse launches many rays from the source. A ray travels in a straight line at the speed of sound (343 m/s) until it hits a wall, where it reflects specularly — the angle of incidence equals the angle of reflection, exactly like light off a mirror. On every bounce the ray's energy is multiplied by (1 − α), where α is that wall's absorption coefficient, so hard tile barely dents the energy while acoustic foam eats most of it.
The room's reverberation time is estimated two ways. The Sabine equation RT60 = 0.161·V/A gives the classic statistical-acoustics prediction straight from geometry: V is the room volume in m³ and A = Σ(Si·αi) is the total absorption in metric sabins, summed over every wall, the floor and the ceiling. The measured value instead times how long the ray population actually takes to decay 60 dB (a millionth of its starting energy) in this simulation — the echogram at the bottom of the canvas plots that decay in real time after each pulse.
- Tile / hard surface — α ≈ 0.03, reflects almost everything, long reverberant tail.
- Carpet — α ≈ 0.30, moderate absorption, shortens the tail noticeably.
- Acoustic foam — α ≈ 0.80, absorbs most incident energy, near-dead room.
This is the flat 2D companion to the 3D acoustic-chamber simulation: the same specular-reflection, absorption-per-bounce and Sabine RT60 physics, viewed from directly above the room.