Watch sound bounce around a room in real time. See wavefronts propagate from a source,
reflect off walls, and decay as materials absorb their energy. Adjust room size, wall material,
and source position to see how reverberation time changes — the key to why some rooms
sound brilliant and others sound like a bathroom.
Exhibit A · The living room
Sound propagation and reverberation
What you're seeing. Concentric circles are wavefronts expanding from the sound source
at 343 m/s (speed of sound). When they hit a wall, they reflect — the reflected wave is dimmer
because the wall absorbed some energy. The Sabine equation calculates reverberation
time (RT60): how long it takes for sound to decay by 60 dB. A living room should be 0.4–0.6s;
a concert hall 1.5–2.0s; an anechoic chamber nearly 0s.
Exhibit B · Material absorption
How much sound does each surface absorb?
Sound absorption coefficient (α) ranges from 0 (perfect reflector) to 1 (perfect absorber).
Concrete reflects 96% of sound. Carpet absorbs 55%. Acoustic foam absorbs 85%.
A room's total absorption is the sum of each surface area × its coefficient.
More absorption = shorter reverb = clearer speech but "deader" music.