To loop a sound is to continuously repeat it. Pierre Schaeffer used looping to draw the listener’s focus away from the source of the sound, and towards the rhythm and texture characteristics within the sound itself.
A loop is a segment of sound that repeats a number of times.
The term originated in the days when sounds were recorded onto analogue magnetic tape. Composers cut pieces of magnetic tape and then joined them back to themselves in order to make a circle of tape called a loop that went round and round. Loops are used to create repeated patterns of sound.