so many possibilities with this.
"A hovering object that explores and manipulates transitional public spaces with particular acoustic properties. By constantly recording and replaying these ambient sounds, the hovering sphere produces a delayed echo of human activity. Space Replay responds sonically to people and its surroundings by means of a battery-powered Arduino, a Wave Shield hacked to record and playback audio and a small speaker. These were inserted into the balloon after being vacuum formed in the shape of a cone, in order to enhance the sound coming from the speaker."