"Pendulum Music" is the name of a work by Steve Reich

Steve Reich

Stephen Michael "Steve" Reich is an American composer who together with La Monte Young, Terry Riley, and Philip Glass is a pioneering composer of minimal music...

, involving suspended microphone

Microphone

A microphone is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. In 1877, Emile Berliner invented the first microphone used as a telephone voice transmitter...

s and speakers, creating phasing

Phasing

In the compositional technique phasing, the same part is played on two musical instruments, in steady but not identical tempo...

 feedback

Feedback

Feedback describes the situation when output from an event or phenomenon in the past will influence an occurrence or occurrences of the same Feedback describes the situation when output from (or information about the result of) an event or phenomenon in the past will influence an occurrence or...

 tones. The piece was composed in August 1968 and revised in May 1973.

Reich came up with the concept while working at the University of Colorado

University of Colorado at Boulder

The University of Colorado Boulder is a public research university located in Boulder, Colorado...

. He was swinging a microphone in the style of the cowboy

Cowboy

A cowboy is an animal herder who tends cattle on ranches in North America, traditionally on horseback, and often performs a multitude of other ranch-related tasks. The historic American cowboy of the late 19th century arose from the vaquero traditions of northern Mexico and became a figure of...

's lasso

Lasso

A lasso , also referred to as a lariat, riata, or reata , is a loop of rope that is designed to be thrown around a target and tighten when pulled. It is a well-known tool of the American cowboy. The word is also a verb; to lasso is to successfully throw the loop of rope around something...

, and noting the produced feedback, he composed for an "orchestra" of microphones.

Three or more microphones are suspended above the speakers by means of a cable

Cable

A cable is two or more wires running side by side and bonded, twisted or braided together to form a single assembly. In mechanics cables, otherwise known as wire ropes, are used for lifting, hauling and towing or conveying force through tension. In electrical engineering cables are used to carry...

 and stand. The microphones are pulled back, switched on, and released over the speaker, and gravity causes them to swing back and forth as pendulum

Pendulum

A pendulum is a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced from its resting equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward the equilibrium position...

s. As the microphone nears the speaker, a feedback tone is created. The music created is then the result of the process of the swinging microphones.

"The piece is ended sometime shortly after all mikes have come to rest and are feeding back a continuous tone by performers pulling the power cords of the amplifiers". "If it's done right, it's kind of funny".

Reich's 1974 book Writings About Music contains the hand-written (1973 revision) description of how to perform the piece.

"Writings About Music" contains a photo of a performance at the Whitney Museum of American Art

Whitney Museum of American Art

The Whitney Museum of American Art, often referred to simply as "the Whitney", is an art museum with a focus on 20th- and 21st-century American art. Located at 945 Madison Avenue at 75th Street in New York City, the Whitney's permanent collection contains more than 18,000 works in a wide variety of...

 on May 27, 1969. The performers there were Richard Serra

Richard Serra

Richard Serra is an American minimalist sculptor and video artist known for working with large-scale assemblies of sheet metal. Serra was involved in the Process Art Movement.-Early life and education:...

, James Tenney

James Tenney

James Tenney was an American composer and influential music theorist.-Biography:Tenney was born in Silver City, New Mexico, and grew up in Arizona and Colorado. He attended the University of Denver, the Juilliard School of Music, Bennington College and the University of Illinois...

, Bruce Nauman

Bruce Nauman

Bruce Nauman is a contemporary American artist. His practice spans a broad range of media including sculpture, photography, neon, video, drawing, printmaking, and performance. Nauman lives in Galisteo, New Mexico....

 and Michael Snow

Michael Snow

Michael Snow, CC is a Canadian artist working in painting, sculpture, video, films, photography, holography, drawing, books and music.-Life:...

.

Notable recordings

Experimental rock group Sonic Youth

Sonic Youth

Sonic Youth is an American alternative rock band from New York City, formed in 1981. The current lineup consists of Thurston Moore , Kim Gordon , Lee Ranaldo , Steve Shelley , and Mark Ibold .In their early career, Sonic Youth was associated with the No Wave art and music scene in New York City...

 recorded the piece for their 1999 album SYR4: Goodbye 20th Century

SYR4: Goodbye 20th Century

SYR4: Goodbye 20th Century is a double album of covers of avant-garde recordings by Sonic Youth and collaborators.SYR4 features works by avant-garde classical composers such as John Cage, Yoko Ono, Steve Reich, and Christian Wolff played by Sonic Youth along with several collaborators from the...

. The Avant Garde Ensemble have recorded three different versions of "Pendulum Music".