Reverberation or echo is the sound that reverberates in the room when the original sound is switched off. The duration of this reverberation field is called the reverberation time and is composed of the first room reflections, the Early Decay Time( EDT), and the diffuse reverberation plume that follows.
Reverberation depends on the room size and its nature and represents the decay process of sound in a room. The immediate reflections on a sound come from the walls, ceilings and floors of the sound room. The following diffuse reflections, expressed in the reverberation plume, are reflections of reflections.
In audio, reverberation makes room sound seem more voluminous and adds warmth and size. For this reason, reverberation is created with a reverberation device in audio recordings and added to the recording.