29 x 43 x 10in

Grace is a clock that chimes each hour . An eight-bit cpu controls an ultrasonic rangefinder, 2-channel sound generating circuitry, and devices that sense ambient light and temperature. Grace senses the distance and motion of a viewer and presents an audio composition it has formed during it's sleep period - which it enters when a viewer is not sensed.
All the qualities of the sound - the pitch, timbre, and loudness - are controlled and modified by Grace with variables that are influenced by the sensed environment. It uses the current state of these variables when it chimes the hour, making a different sound each time. I'm convinced Grace is smart enough to never repeat a composition exactly.
This machine responds to viewer activity in several ways, but will ignore gross movement such as jumping and waving. It seems to ignore a viewer wearing a billed hat backwards.

High-res image

This note was found on Grace during an exhibit in Seattle.

Someone had molested the machine several times before the note appeared.