Psychedelic music is a musical genre inspired by or attempting to
replicate the mind-altering experience of drugs such as cannabis,
psilocybin, mescaline, and especially LSD. It is not rigorously defined, and
is sometimes interpreted to include everything from Acid Rock and Flower
Power music to Hard Rock. However, an inner core of the genre that came to
public attention in 1967 can be recognized by characteristic features such
as modal melodies; esoteric lyrics often describing dreams, visions, or
hallucinations; longer songs and lengthy instrumental solos; and recently
invented "trippy" electronic effects such as distortion, reverb,
and reversed, delayed and/or phased sounds. The album that brought
psychedelic rock into pop culture was The Beatles's Sgt. Pepper's Lonely
Hearts Club Band.
While the first musicians to be influenced by psychedelic drugs were in
the jazz and folk scenes, the first use of the term "psychedelic"
in popular music was by the "acid-folk" group The Holy Modal
Rounders in 1964. The first use of the word "psychedelic" in a
rock music context is usually credited to the 13th Floor Elevators, and the
earliest known appearance of this usage of the word in print is in the title
of their 1966 album The Psychedelic Sounds of the 13th Floor Elevators.
The psychedelic sound itself had been around at least a year earlier in the
live music of the Grateful Dead and Pink Floyd, and Donovan's hit Sunshine
Superman. The genre reached its maximum popularity in 1967 and then
quickly tapered off, though a number of bands continued and there has been a
revival since the 1980s.