Shown above is the tetrahedral microphone array Dan uses to record his soundscapes, three of which he played back on the ACTlab’s surround-sound system. The tetrahedral microphone arrangement makes it possible to mathematically derive any number or spatial arrangement of surround-sound channels from the raw audio. Professional ambisonic microphones cost thousands of dollars; Dan put his together for nine bucks. He played amazing recordings of a babbling river, a clowder of feeding cats, and a pipe organ recital at UT’s Bass Concert Hall, while the audience milled about the room to experience the spatial simulation of the original sounds. The realism was absolutely uncanny. There’s more info on Dan’s Soundscapes page.