Psychedelic rock emerged in the mid-'60s, as British Invasion and folk-rock bands began expanding the sonic possibilities of their music. Instead of confining themselves to the brief, concise verse-chorus-verse patterns of rock & roll, they moved toward more free-form, fluid song structures. Just as important -- if not more so -- the groups began incorporating elements of Indian and Eastern music and free-form jazz to their sound, as well as experimenting with electronically altering instruments and voices within the recording studio. Initially, around 1965 and 1966, bands like the Yardbirds and the Byrds broke down the boundaries for psychedelia, creating swirling layers of fuzz-toned guitars, sitars, and chanted vocals.
