Positional audio (with its attenuation, speaker placement, and Doppler effect) comprises the most fundamental level of 3D audio. Now we will cover some advanced techniques that we can use on top of positional audio to provide a more complete simulation of how sounds interact with the environment. One of those techniques is called reverberation, or reverb.
Reverb is the capability of sound to persist in a particular space for some time after the original sound has stopped. We can think of reverb as a succession of echoes with very little time in between them.
Reverb occurs because most audio sources project sound in several directions at once. Some of those sound waves reach our ears directly, in the shortest path possible. Others, however, head in different directions, and reflect off various surfaces, such as walls, before finally reaching our ears. These reflected sound waves take longer to reach our ears than the direct sound waves, and become quieter with every bounce they make...