"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":
It's been a hard days night
And I've been working like a dog
For 40 years, no one has been able to accurately chart what Harrison was playing. By decomposing the sound into its original frequencies using computer software, Halifax mathematician Jason Brown has finally figured out the mystery chord.