Phil Kline’s Unsilent Night is a free outdoor participatory sound sculpture of many individual parts, recorded on cassettes, CDs and mp3s, which are played through a roving swarm of boomboxes carried through city streets every December. People bring their own boomboxes and drift peacefully through a cloud of sound which is different from every listener’s perspective. Since 1992, this 45-minute work has grown into a worldwide annual communal event that has become an essential part of many winter holiday celebrations.