Folk rock is a musical genre combining elements of folk music and rock music. In its earliest and narrowest sense, the term referred to a genre that arose in the United States and the UK around the mid-1960s. The sound was epitomized by tight vocal harmonies and a relatively "clean" (effects- and distortion-free) approach to electric instruments epitomized by the jangly 12-string sound of the Byrds' guitarist Roger McGuinn as used sparingly by George Harrison in 1964 and 1965. The repertoire was drawn in part from folk sources, but even more from folk-influenced singer-songwriters such as Bob Dylan. Roger McGuinn of the Byrds has also stated The Beatles inspired him to mix folk with rock music. Allmusic also credits The Beatles, along with Dylan, as being heavily influential on the folk rock explosion of 1965.