A Guest Post by the Chief of Photography
Although here in the photography department we don’t usually deal with these kinds of things, I can explain what happens in the following video (or actually, Wikipedia can) as a “wave that has been reflected by a discontinuity in the propagation medium, and returns with sufficient magnitude and delay to be perceived”.
Here’s an example of a “reflection of sound, arriving at the listener some time after the direct sound” in AMG’s room before any furniture was put in. (Turn on your speakers before clicking play):
If you can’t see the video, click here.
Please note that since I took this video, some furniture has been added.