Türen der Wahrnehmung (Doors of Perception) piece was commissioned by the Östereichischer Rundfunk (ORF) for Ars Electronica '89 in Linz, Austria. In its entire length it is 30 minutes long and was broadcast into public urban places in Linz during Ars Electronica. The sound materials for the piece were taken from the European sound collection of the World Soundscape Project at Simon Fraser University in Vancouver and from the composer's own collection of field recordings made in Europe as well as in Canada. Türen der Wahrnehmung: a door opens and we enter another sound world. A new sonic space surrounds us and we listen. More and more doors open and we do not know what will meet us. Our ears are alerted. Radio can open many doors to new (and old) sound worlds. The creaking door of a radio drama takes us into a haunted place, a closet door perhaps into Lewis' "Narnia", another door leads us into the wilderness, yet another to the train station, into the streets, near a creek, to another continent, or simply into the world of acoustic imagination. Indeed radio can listen into all corners of life.
Excerpts of Türen der Wahrnehmung have been used in Gus Van Sant's films Elephant and Last Days. See Randolph Jordan's article: "The Work of Hildegard Westerkamp in the Films of Gus Van Sant"