Diffuse acoustic field (reverberant)

Professional Definition

The acoustic field in a room, created by the multiple reflections of sound waves from the surfaces that limit the given room.

In contrast to the free field, the dominant role in the reverberant field is played by the energy of the reflected waves. The acoustic pressure level in this area is approximately constant and weakly dependent on the distance from the source. It is the characteristic of the scattered field that determines the reverberation time ($ RT_{60} $) inside. In large, poorly damped halls, this field occupies the majority of the volume.

Acoustics in Simple Words

Imagine a billiard table on which you throw a hundred balls at the same time. The first hit is a direct wave, but shortly after, the balls bounce off the rails and off each other in a chaotic manner, filling the entire table with movement. This is the reverberant field. If you are in a large swimming pool hall and someone shouts from the other end, you hear that shout, but it is blurred, reaching you from "everywhere" and lasting longer than the actual opening of the mouth by the person shouting. You hear not so much the source, but the room's response to that source.

Summary

The scattered (reverberant) acoustic field is the sum of all sound reflections inside. Controlling this field through absorption and diffusion is the main task of the acoustical engineer during the adaptation of office spaces or concert halls.