as the beatles pioneered the use of "musique concrète" in pop music (i.e. the sped-up tape loops in "tomorrow never knows"), backward recordings came as a natural exponent of this experimentation. "rain", the first rock song featuring a backwards vocal (lennon singing the first verse of the song), came about when lennon (claiming the influence of marijuana) accidentally loaded a reel-to-reel tape of the song on his machine backwards and essentially liked what he heard so much he quickly had the reversed overdub. a quick follow-up was the reversed guitar on "i'm only sleeping", which features a dual guitar solo by george harrison played backwards. harrison worked out a forward guitar part, learned to play the part in reverse, and recorded it backwards. likewise, a backing track of reversed drums and cymbals made its way into the verses of "strawberry fields forever". the beatles' well-known use of reversed tapes led to rumours of backwards messages, including many that fueled the paul is dead urban myth. however, only "rain" and "free as a bird" include intentional reversed vocals in beatles songs.