Gnomon is a group of sound-producing bodies, each whose form and
resonance are determined by an audio feedback loop. The sound
producing element in each body is a thin metal wire that contracts
and relaxes in proportion to the amount of signal passing through
it. This wire holds a bronze sheet in tension and is connected
to the speaker terminals of an audio amplifier. The amplifier
receives its input from a contact microphone placed on the sheet,
and a magnet placed under the wire makes it vibrate audibly when
an audio signal is passed through the wire.
This system constitutes a feedback loop that dynamically determines
the shape, motion and sound the bronze sheet produces. However,
environmental variations such as temperature, humidity, air currents
and ambient sound serve to disrupt this stability, producing
changes over time.
Each sound body is approximately
24" x 6" and is suspended from the ceiling. Installation
can include from as little as one body to as many as there are
audio input/output channels. Gnomon has currently been redesigned
to be powered not only by the grid, but also solar panels, and
has appeared in Solar One's CitySol
2007 festival.