While in Denver for the Chaser Con, we went to see one of Christopher Janney's interactive art pieces, "Harmonic Pass" which is built into a tunnel under I-25 as part of the Southmoor RTP light rail stop.
I met Mr. Janney at LDI many years ago, and his pieces which I have seen have typically involved interactive lighting and sound, and are permanently installed in public places. This one is simple but interesting:
If you pass close to the vertical fixtures, they turn off and generate a tone. We watched a few commuters go through it, and it was interesting to see how they reacted. The sensors only respond to people close to the sides of the tunnel, so it's possible to walk right through the middle without triggering it. Most of the commuters, who likely had seen the piece many times, just walked through, sometimes triggering it, sometimes not.
The system goes into a little automatic loop at some interval as well.
The piece is also very responsive, so of course we went up and played with the sensors directly.
Mr. Janney is also doing a in March called HeartBeat with The Persuasions up in Concord, Mass as a benefit for Summerstages Dance. Janney was recently on WNYC's excellent show Soundcheck talking (singing) about this piece.