"I wanted to clean the interior of my car and the electrical cord of the vacuum
cleaner was too short. Rather than use an extension cord, I added an additional
tube to the vacuum cleaner hose; a quite surprising sound ensued."
Schwirrer, built in 2000, is based on a principle similar to that of an organ or flute in which
a column of air is caused to vibrate when air is forced into a tube. For Schwirrer, Christof
Schläger uses internally fluted tubes rotated by motors. The action of rotating causes air to
flow through the fluted tubes. The parallel fluting within the tube generates standing waves of
air similar to the aquatic action in a small brook where extending from the banks crosswise
overlapping waves are formed on the surface of the water. This rhombic pattern of the brook
generates visible standing waves. In the same way sound waves are formed in the tube where the
junctions are perceived as sounds. A higher airflow generates a natural overtone series. A
Schwirrer of seven meters in width and three and a half meters high supports eight of these
rotating tubes of various thickness and length in order to be able to produce basic sounds of
various pitches. Schläger combines up to eight Schwirrers and therefore has 64 sounds plus
their respective overtones available.