Reverb explained
Reverberation is created when a dry sound or signal is reflected in a space, bouncing against walls, floors, ceilings before gradually losing energy. The reflections eventually decrease until the reflections are absorbed. Reverberation is more noticeable in larger spaces such as churches and large empty rooms etc. but is audibly noticeable in much smaller spaces too.
Reverberation time is commonly measured as RT60, the time in which it takes the sound level to decrease by 60db. Rooms with an RT60 time of less than 0.3 seconds are flat and ‘dead’, whereas rooms with an RT60 time of more than 2 seconds have an echo.
Reverb can be an issue for certain scenarios, for example in a recording studio when you need a precise, direct sound and accurate response, or in a classroom or theatre where an echo would make it difficult to understand speech, but reverb has also been used on purpose as an effect for many years in music.