It’s the most famous chord in rock 'n' roll, an instantly recognizable twang rolling through the open strings on George Harrison’s 12-string Rickenbacker. It evokes a Pavlovian response from music fans as they sing along to the refrain that follows:Professor Jason Brown of Dalhousie University’s Department of Mathematics decided to apply a mathematical calculation known as a Fourier transform to solve the problem"It’s been a hard day’s nightThe opening chord to "A Hard Day’s Night" is also famous because, for 40 years, no one quite knew exactly what chord Harrison was playing.
And I’ve been working like a dog"
The resulting chord was completely different than anything found in the literature about the song to date, which is one reason why Dr. Brown’s findings garnered international attention. He laughs that he may be the only mathematician ever to be published in Guitar Player magazine.For the full technical presentation of Brown's triumph, see CHAAAAAAAAG...It's been a hard day's night! and, perhaps, Wired's How Math Unraveled the 'Hard Day's Night' Mystery.
(By the way, in case you need a reminder about the opening chord, here is a copy from the Wired article: