<P> Harrison echoed Martin's description of his stabilising role: "I think we just grew through those years together, him as the straight man and us as the loonies; but he was always there for us to interpret our madness--we used to be slightly avant - garde on certain days of the week, and he would be there as the anchor person, to communicate that through the engineers and on to the tape ." </P> <P> Making innovative use of technology while expanding the possibilities of recorded music, the Beatles urged experimentation by Martin and his recording engineers . 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 . 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 Geoff Emerick, all contributed significantly to their records from Rubber Soul and, especially, Revolver onwards . Along with innovative studio techniques such as sound effects, unconventional microphone placements, tape loops, double tracking and vari - speed recording, the Beatles augmented their songs with instruments that were unconventional in rock music at the time . These included string and brass ensembles as well as Indian instruments such as the sitar in "Norwegian Wood" and the swarmandal in "Strawberry Fields Forever". They also used novel electronic instruments such as the Mellotron, with which McCartney supplied the flute voices on the "Strawberry Fields Forever" intro, and the clavioline, an electronic keyboard that created the unusual oboe - like sound on "Baby, You're a Rich Man". </P> <P> Former Rolling Stone associate editor Robert Greenfield compared the Beatles to Picasso, as "artists who broke through the constraints of their time period to come up with something that was unique and original...(I) n the form of popular music, no one will ever be more revolutionary, more creative and more distinctive ..." The British poet Philip Larkin described their work as "an enchanting and intoxicating hybrid of Negro rock - and - roĺl with their own adolescent romanticism", and "the first advance in popular music since the War". They not only sparked the British Invasion of the US, they became a globally influential phenomenon as well . From the 1920s, the United States had dominated popular entertainment culture throughout much of the world, via Hollywood movies, jazz, the music of Broadway and Tin Pan Alley and, later, the rock and roll that first emerged in Memphis, Tennessee . The Beatles are regarded as British cultural icons, with young adults from abroad naming the band among a group of people that they most associated with UK culture . </P> <P> Their musical innovations and commercial success inspired musicians worldwide . Many artists have acknowledged the Beatles' influence and enjoyed chart success with covers of their songs . On radio, their arrival marked the beginning of a new era; in 1968 the programme director of New York's WABC radio station forbade his DJs from playing any "pre-Beatles" music, marking the defining line of what would be considered oldies on American radio . They helped to redefine the album as something more than just a few hits padded out with "filler", and they were primary innovators of the modern music video . The Shea Stadium show with which they opened their 1965 North American tour attracted an estimated 55,600 people, then the largest audience in concert history; Spitz describes the event as a "major breakthrough...a giant step toward reshaping the concert business". Emulation of their clothing and especially their hairstyles, which became a mark of rebellion, had a global impact on fashion . </P>

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