How can sound-absorbing materials reduce reverberation in a room?

Sound-absorbing materials reduce reverberation in a room by increasing the total sound absorption of the space, which accelerates the decay of reflected sound waves.12

When a sound source stops, the sound heard in a room continues for a period known as the reverberation time—the time required for the sound intensity to drop by 60 decibels. In an empty room with hard surfaces, sound waves reflect repeatedly with little loss of energy, leading to a long, prolonged reverberation.12

By introducing materials with high absorption coefficients—such as acoustic boards or curtains—the surfaces of the room capture a greater fraction of the sound energy upon each reflection. This process converts the coherent molecular motion of the sound wave into heat, effectively removing energy from the room and causing the reverberant sound to decay more rapidly. Architects and engineers use the empirical relationship $RT=0.05V/A$ (where $V$ is volume and $A$ is total absorption) to predict and modify these characteristics, ensuring the room's acoustics are suitable for their intended purpose, such as speech clarity or musical performance.13