Acoustics

Sound is what happens when air gets pushed. These pushes become audible when they repeat rapidly, from around 20 times a second to 20,000. This action of repeated pushes can be actually seen in say a Bass Drum or a Bass Loudspeaker cone. Each push causes a wavefront of high pressure. These Wavefronts of high pressure make their way to the boundaries of the room. Then they are either absorbed by soft surfaces such as carpets or curtains, or the bounce back fully from hard surfaces such as glass, tile, or brick. They will then ping pong between opposing boundaries, losing a little energy in each bounce, eventually fading away. The length of time this fade takes is the Reverb Time (RT). Typical living rooms would have RT in the region of half a second. In large spaces the distance travelled on each bounce is longer, taking a longer time. Concert Hall RT can be several seconds long.

Such long RTs are suited to Classical music, but can make Rock music very blurred with each drum beat echoing around for seconds. In the past RT was measured using a stopwatch and a starters pistol. These days we use software.