In 1966, the level of social and artistic correspondence among British and American rock musicians dramatically accelerated for bands like the Beatles, the Beach Boys and the Byrds who fused elements of cultivated music with the vernacular traditions of rock. Progressive rock was predicated on the "progressive" pop groups from the 1960s who combined rock and roll with various other music styles such as Indian ragas, oriental melodies and Gregorian chants, like the Beatles and the Yardbirds. The Beatles' Paul McCartney said in 1967: "we band got a bit bored with 12 bars all the time, so we tried to get into something else. Then came Dylan, the Who, and the Beach Boys. ... We're all trying to do vaguely the same kind of thing." Rock music started to take itself seriously, paralleling earlier attempts in jazz (as swing gave way to bop, a move which did not succeed with audiences). In this period, the popular song began signalling a new possible means of expression that went beyond the three-minute love song, leading to an intersection between the "underground" and the "establishment" for listening publics.