Via the Beeb:
"People forget that it's just a young band playing in the studio," says Martin. "Everything is fairly aggressive. Everything is in your face. Everything the Beatles recorded is a little bit louder than you think it is."
Eleanor Rigby is a perfect example. Instead of using the string section as a soft underscore, Paul asked them to play in sharp, staccato stings inspired by Bernard Herrmann's score for Alfred Hitchcock's Psycho.
"Which is a funny influence if you think about it - you take the shower scene with a woman being stabbed and put it on Eleanor Rigby," reflects Martin.
An expanded, deluxe edition of Revolver captures the strings being recorded at Abbey Road, with Giles's father George Martin arranging the musicians on the fly.
"Do you want them to play the chords without vibrato?" he asks McCartney, who listens to several options before declaring he can't tell the difference.
"All those years of learning," the musicians grumble good-naturedly, "and he says it sounds the same."
McCartney eventually opts to lose the vibrato, giving the recording its razor-sharp immediacy.
"What impresses me is the speed of thought," says Martin. "You have to remember that 10 minutes before that conversation, no-one would have ever heard the Eleanor Rigby strings before. It's an amazing session."