31 Jan 2009

# The Beatle’s Unduplicatable First Chord

### Beatles, Mathematics, Music, Rock & Roll

Jason Brown, Chairman of the Mathematics Department at Dalhousie University, applies math to solving a musical mystery.

Wall Street Journal

It is here, in a cluttered mathematician’s office, under blackboards jammed with equations and functional analysis, that one of Western culture’s greatest mysteries has finally been solved: Why has no one been able to replicate the first chord in The Beatles’ pop hit “A Hard Day’s Night”? …

Mr. Brown realized he could use a discrete Fourier transform, a mathematical technique for breaking up complicated signals into simpler functions and known as DFT. He used digital equipment to show the chord as a series of numbers, tens of thousands per second, and then applied a DFT to convert the chord into dozens of simpler functions, each representing a single sound frequency.

Mr. Brown knew there is no such thing as a pure tone: Each instrument emits one sound for the note played and then sounds that are multiples of that note’s frequency, as the string vibrates back on itself. Of his dozens of frequencies, some were background noise and some–the ones he wanted to ferret out–were the notes the Beatles struck.

The professor started making deductions. The loudest notes were likely Mr. McCartney’s bass. The lowest had to be the original note played, since a string can generate waves along half or a third of its length, but not twice its length. But no matter how he divvied up the notes, something didn’t fit.

It is well-documented that Mr. Harrison played a 12-string guitar for the recording of “A Hard Day’s Night.” For every guitar note played, there had to be another one octave higher, since his guitar strings were pressed down in pairs.

But three frequencies for an F note were left, none of which were an octave apart. Even if Mr. Brown assumed Mr. Lennon played one F note on his six-string guitar, Mr. Brown still had two unexplained frequencies.

After weeks of staring at six-decimal-place amplitude values, Mr. Brown suddenly remembered how, as a child, he used to stick his head inside his parents’ grand piano to see how it worked. He ran to a nearby music shop, and poked his head inside the Yamahas there.

Sure enough, there were three strings under the F key, corresponding to the three sets of harmonics he had seen. Buried under the iconic guitar chord was a piano note.

Other problems have since yielded to Mr. Brown’s mathematics. Fans have always marveled at Mr. Harrison’s guitar solo in “A Hard Day’s Night,” a rapid-fire sequence of 1/16th notes, accompanied on piano, that seemed to require superhuman dexterity.

Mr. Brown noticed that a piano is strung differently in its lower octaves, with two strings, rather than three, under each hammer. He saw only two frequencies for each piano note in the guitar solo, suggesting that the solo had been played one octave lower than the recorded version sounded. It had also been played at half-speed, he concluded, then sped up on tape to make the released version sound as if had been played faster and at a higher octave.

2:33 video

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