While chasing details to link to in recent posts on PDM and sound I tripped over this blog from a professor of acoustic and audio engineering who has at his disposal a decently sized real anechoic chamber.

Apparently a favorite demo he does for visitors is to pop a balloon in it, which emphasizes the importance of the live room echoes to how we perceive sounds. Here’s his post on the subject where he includes audio of a balloon and firing a starter pistol.