Location. Stairwell leading from first-floor lobby to basement of Thatcher Music Building, Pomona College, Claremont, CA.

Description of the space. It is an enclosed two-flight staircase.  The walls, which include a wall separating the two flights of stairs, are of painted concrete.  The steps and landing are covered in laminate tile and appear to be concrete underneath.  The stairwell has doorways at top and bottom, usually open, for entry and exit.  They were open during this recording.  The ceiling is at an angle, so that the distance above any step is approximately approximately ?? feet.  Total height of the stairwell from the bottom landing to the ceiling above the top landing is approximately ?? feet.

Recording setup. The microphone and the balloon were both placed near the floor of the landing between the two flights of stairs, about three feet apart.

Reverberation time.
30 dB decay:  1.8 sec
60 dB decay:  4.8 sec
decay to background level: 5.0 sec
minimum: 6.4 sec
(Using intensity graph function in Praat,)

Acoustic description.  The resonance in this space prominently reinforces a pitch that I hear as 312 Hz. In the recording this pitch (E-flat 3, just above middle C) becomes audible as a hum less than a half-second after the pop, and it remains perhaps the most prominent feature of the sound for about two seconds.