Sgt. Pepper's Lonely Hearts Club Band "Being for the Benefit of Mr. Kite!" and "A Day in the Life". Producer George Martin and engineer Geoff Emerick helped realise the group's ideas by approaching the studio as an instrument, applying orchestral overdubs, sound effects and other methods of tape manipulation. Recording was completed on 21 April 1967. The cover, depicting the Beatles posing in front of a tableau of celebrities and historical figures, was designed by the British pop artists Peter Blake and Jann Haworth. "Sgt. Pepper" is regarded by musicologists as an early concept album that advanced the use of extended form in popular music while
Sgt. Pepper's Lonely Hearts Club Band with Diamonds" as having the most variations of tape speed on "Sgt. Pepper". During the recording of Lennon's vocals, the tape speed was reduced from 50 cycles per second to 45, which produced a higher and thinner-sounding track when played back at the normal speed. For the album's title track, the recording of Starr's drum kit was enhanced by the use of damping and close-miking. MacDonald credits the new recording technique with creating a "three-dimensional" sound that, along with other Beatles innovations, engineers in the US would soon adopt as standard practice. "Sgt. Pepper" was the first pop album to