Bell in a Bell Jar
"In Space No-one can hear you scream!"
The following video is of one of the classic demonstrations of physics: The Bell in a Bell Jar.
Bell Jars are so named because their shape resembles a bell. The one on the video contains a ringing electric bell, and it also connected to a vacuum pump. When the pump is switched on it starts to remove the air from the jar. Once most of the air has been removed, air is allowed back into the jar.
To appreciate the video it is essential that you have speakers or headphones attached and turned on.