An interpolation or a "replayed sample" is when the sampling track does not use a portion of the actual source recording directly, but reproduces it in some way; in many cases, a replayed sample or interpolation reproduces the exact melody line of another track using a different instrument, or in the case of interpolated vocals, being sung or rapped by another performer.
Interpolation in music is prevalent in all genres of modern music; one early example would be the Beatles interpolating "La Marseillaise", among four other interpolations in the song "All You Need Is Love".
One genre where interpolating (as well as sampling) is highly prevalent is hip hop music; this is due to the original artist or label declining to license the actual direct sample, for the sampling of already-released music is subject to compulsory licenses. Some examples are Mýa singing the hook on "Ghetto Supastar" by Pras that was originally written for the song "Islands in the Stream" by Kenny Rogers and Dolly Parton. "I'll Be Missing You" by Puff Daddy, Faith Evans and 112 contains interpolated vocals of "Every Breath You Take" by the Police, but also directly samples the song's guitar riff throughout. Frank Ocean's "White Ferrari" interpolates the Beatles' "Here, There and Everywhere". Trippie Redd also uses a method of interpolation throughout the hook in his song "Dark Knight Dummo" (feat. Travis Scott), which is reminiscent of Trippie's feature in XXXTentacion's "F**k Love".
Interpolation also refers to a different use of the term in classical music:
Interpolation (also known as replayed), especially in 20th-century music and later, is an abrupt change of musical elements, with the (almost immediate) resumption of the main theme or idea. Pieces that are cited as featuring interpolation, among other techniques, are Music for Brass Quintet by Gunther Schuller and Threnody to the Victims of Hiroshima by Krzysztof Penderecki (both 1960-61).
This device is commonly used to extend what would normally be a regular phrase into an irregular and extended phrase. Such expansion by interpolation is achieved by the addition of extra music in the middle of a phrase (commonly through the use of sequence). A clear example exists in the second movement of Mozart's Piano Sonata No. 10, K.330.
Formerly, in the sung portions of the Mass, such as the introit or kyrie, it was permissible, especially during the medieval period, to amplify a liturgical formula by interpolating a "farse" (from Medieval Latin farsa, forcemeat),[clarification needed] also called "trope". This might consist of an explanatory phrase or verse, usually in the form of an addition or paraphrase, often in the vernacular.