In the studio

The Beatles made innovative use of technology, expanding the possibilities of recorded music. They urged experimentation by Martin and his recording engineers, while seeking ways to put chance occurrences to creative use. Accidental guitar feedback, a resonating glass bottle, a tape loaded the wrong way round so that it played backwards—any of these might be incorporated into their music.^[315] Their desire to create new sounds on every new recording, combined with Martin's arranging abilities and the studio expertise of EMI staff engineers Norman Smith, Ken Townsend, and Emerick, all contributed significantly to their records from Rubber Soul and, especially, Revolver forward.^[315] Along with innovative studio techniques such as sound effects, unconventional microphone placements, tape loops, double tracking and vari-speed recording, they augmented their songs with instruments that were unconventional for rock music at the time. These included string and brass ensembles as well as Indian instruments such as the sitar in "Norwegian Wood (This Bird Has Flown)" and the swarmandal in "Strawberry Fields Forever".^[316] They also used early electronic instruments such as the Mellotron, with which McCartney supplied the flute voices on the "Strawberry Fields" intro,^[317] and the clavioline, an electronic keyboard that created the unusual oboe-like sound on "Baby, You're a Rich Man".^[318]