The opening chord of "A Hard Day's Night"

The jangly opening chord of The Beatles' hit "A Hard Day's Night" is one of the most recognizable in pop music.

Maybe it sounds like nothing more than a guitarist telling his bandmates, "Hey, we're doing a song here, so listen up." But for decades, guitarists have puzzled over exactly how that chord was played.

So a mathematician in Canada looked into how The Beatles produced that sound back in 1964, before the synthesizers and studio electronics available today. Host Scott Simon discusses the findings with the Weekend Edition Math Guy, Stanford professor Keith Devlin.

Read (or listen to) the rest at http://www.npr.org/templates/story/story.php?storyId=98743259">'Hard Day's Night': A Mathematical Mystery Tour

"A Hard Day's Night" is immediately identifiable before the vocals even begin, thanks to George Harrison's unmistakable Rickenbacker 360/12 12-string guitar's "mighty opening chord".<12> According to George Martin, "We knew it would open both the film and the soundtrack LP, so we wanted a particularly strong and effective beginning. The strident guitar chord was the perfect launch"<8> having what Ian MacDonald calls "'a significance in Beatles lore matched only by the concluding E major of "A Day in the Life", the two opening and closing the group's middle period of peak creativity'".<13> "That sound you just associate with those early 1960s Beatles records".<14>

Analysis of the chord has been the subject of considerable debate,<15> with it being described as G7add9sus4,<13> G7sus4,<16><17> or G11sus4<12> and others below.

Read the rest of the wiki entry http://en.wikipedia.org/wiki/A_Hard_Day%27s_Night_(song)#Opening_chord">here.