Reverberation time.
30 dB decay: 1.9 sec
50 dB decay: 3.6 sec
60 dB decay: 4.9 sec

This recording was done in the underground tunnels beneath X and Y towers in Mead Residence Hall at Pitzer College. It is a very small confined space, made primarily of concrete and brick. The area is completely enclosed as is easily heard from the popping of the balloon. The exact point in the tunnel that I chose to pop the balloon in was devoid of any objects except some metal piping that runs throughout the tunnels.