Transition Soundings — an interactive public sound art sculpture by David Birchfield, David Lorig, Kelly Phillips, and Assegid Kidané — is a free standing, fully self contained outdoor installation. Located at a bus stop in Tempe, Arizona, the structure has the appearance of a large transit map with hubs and paths connecting locations across its surface. However, this stylized ‘map’ is actually a large network of sensors and speakers that trace paths in sound across the surface of the wall. As users move and gesture in front of the piece, a network of proximity sensors initiates sonic events that wash across the surface in a fashion that references ripples across the surface of water. Sound events propagate through the network in a way that mimics movement of traffic, ideas, currents, and connections in the networks of our lives.

From November 2005 - April 2006, the work was installed at a bus transit stop in Tempe, AZ located on the NW corner of the intersection of two major streets, Priest and Broadway.

MOTIVATING IDEAS: In conceiving this public work we have built upon the idea of the transit network as a metaphorical and practical sonic force. Topographically, the visual arrangement of speaker placement simulates a transit map that moves from a dense urban arrangement on the left, toward a widely spaced arrangement on the right. As sound moves across the wall, we have modeled the notion that transit paths will evolve and perhaps grow more sluggish with use. Thus, sound travels differently through each node of the network over time. This use of the network as a musical and visual presence, is intended to more broadly reference to role of networks in our lives. Transit networks physically link our communities, but networks of social, intellectual, and cultural connection span our world as well.

As this work is situated in the desert southwest, we also considered environmental issues in its conception. The propagation of sound across the surface of the wall simulates the way that the surface of water will ripple and expand when disturbed. In addition, all the electronics in this work are powered by a solar panel mounted above the work. The use of reusable energy is an important aspect of the work.

REALIZATION: At the heart of the piece is a 6′H x 10′W interactive wall that houses a network of sensors and sound producing elements. This wall is comprised of twenty-six modules that have the same basic design and function. There are two types of modules that, like in a real world transit network, serve as hubs or straight paths. Each module contains two proximity sensors, one light sensor, ten piezo speakers, and one microcontroller computer with supporting circuitry. Adjacent modules are connected to one another such that they form a fully connected network across the entire wall that allows sounds to wash across its surface.

This internal wall of sensor/speakers is enclosed on the back by a solid panel that keeps the elements out of sight and reach of the public. The wall is enclosed on the front side by a porous sheet of metal that provides protection and security, while allowing sound to easily emanate from the speakers, and providing visibility to the sensors and resonators embedded on the inner panels. The total depth of the structure is approximately 8 inches.

A large solar panel is mounted above the wall to generate electricity for the installation and provide protection from the elements. A battery is safely housed within the structure and is recharged by the solar panel to provide power to the electronics during the day and night. The structure is rooted in the ground behind the transit stop, facing, and in close proximity to the bench where transit users converge while waiting.