For this activity, you’ll need an isolated loudspeaker (bare of its casing) and a sheet of plywood or cardboard—the bigger the better. Cut a hole about the size of the speaker in the middle of the sheet. Listen to music from the isolated speaker, and then hear the difference when the speaker is placed against the hole. The sheet diminishes the amount of sound from the back of the speaker that interferes with sound coming from the front side, producing a much fuller sound. Now you know why speakers are mounted in enclosures.