Structural feedback
Compare the two photos below:

Sketch before construction	Finished Product

As you can see, the finished product bears a remarkable resemblance to the original sketch. This I attribute to Shannon’s construction prowess. The loops of audio cable and rope provide a sense of recursive adjustment and feedback while the equilateral nature of the teepee naturally lends itself to loopy thoughts.

Social and Behavioral feedback

Interestingly, our test audiences have established themselves in semi-circles around the piece. By yelling at the piece, or by having a conversations with each other, the viewers can alter the behavior of the teepee as it tries to maintain a constant sound level. An interesting result involves yelling into the suspended microphone and having your voice trigger a feedback loop. The leisurely speed of the movement also seems organic. The microphone is very responsive, but “heavy”.

Technical details
Many of the behavioral responses are a result of mapping a non-linear input onto a linear output. Feedback is a non-linear function of the distance from microphone to speaker, and other environmental conditions while the movment of the microphone is a linear constant.

The BX-24 microcontroller is running this code. It is taking samples of the ambient noise level using a small electret microphone running through an LM386 amplifier. The ambient sound level is extremely “bouncy”, so we are taking the standard deviation of the noise levels as our input, not the noise levels themselves. This works famously. The BX-24 then controls a home-made H-Bridge to move a motor forward or backward. Forward motion raises the microphone via pulleys to lower the sound level, and backward – as you’d expect – does the opposite.