Although our post Moogfest event was altered due to lack of electricity, iBoD did regale our audience with an acoustic improv for about a half hour. Eleanor and I played the tank bells, while Jim played his horn and Susanne played Native American flute.
Towards the end, it was suggested that Eleanor and I get two of the smaller tank top bells going like singing bowls, while Jim and Susanne improvised over them. The harmonics were so dense that we had a lot of fluttering beats moving in and out, which I loved. You will hear traffic creating Doppler effects, chattering people and birds, and the beating of some very big wings!
Here is that improv which I named Cosmic Iron Butterfly: