Loop pedal

In music, tape loops are loops of magnetic tape used to create repetitive, rhythmic musical patterns or dense layers of sound when played on a tape recorder. Originating in the 1940s with the work of Pierre Schaeffer, they were used among contemporary composers of 1950s and 1960s, such as Steve Reich, Terry Riley, and , who used them to create phase patterns, rhythms, textures, and timbres. Popular music authors of 1960s and 1970s, particularly in psychedelic, progressive and ambient genres, used tape loops to accompany their music with innovative sound effects. In the 1980s, analog audio and tape loops with it gave way to digital audio and application of computers to generate and process sound.

In a tape loop, sound is recorded on a section of magnetic tape and this tape is cut and spliced end-to-end, creating a circle or loop which can be played continuously, usually on a reel-to-reel machine.

By accelerating the speed of a loop to a sufficient degree (e.g., 1,280 times faster), a sequence of events originally perceived as a rhythm becomes heard as a pitch, and variation of the rhythm in the original succession of events produces different timbres in the accelerated sound (, 42; , 362–63).

Simultaneous playing of tape loops to create phrase patterns and rhythms was developed and initially used by musique concrète and tape music composers, and was most extensively utilized by Steve Reich for his "phasing" pieces such as "Come Out" (1966) and "It's Gonna Rain" (1965), and by Karlheinz Stockhausen in Gesang der Jünglinge (1955–56) and (1958–60). Stockhausen also used the technique for live performance in (1965–66).

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