Both Paul McCartney's "P. S. I Love You" and John Lennon's "Please Please Me" employ a particular technique known as oblique motion, where one voice remains on a single note while the other voice moves (ascending, descending, or a combination).
In "P. S.", this oblique motion can be heard three times on the words "be in love with you" at 0:11-0:13, 1:01-1:03, and 1:33-1:35.
Paul's higher melodic vocals move from note to note, while John's lower vocals remain stationary on a low A.
Lennon borrowed the technique (but inverted) for "Please Please Me", heard twice in each of the three verses for a total of six times at 0:08-0:12, 0:15-0:19, 0:35-0:39, 0:42-0:46, 1:20-1:24, 1:27-1:31.
Lennon's lower melodic vocals move from note to note, while Paul's upper vocals remain stationary on a high E.
Both Beatles' use of oblique motion likely comes from the song "Cathy's Clown" by the Everly Brothers, who sing using oblique motion thrice in each of the three verses for a total of nine times, heard at 0:08-0:11, 0:16-0:19, 0:32-0:35, 0:56-0:59, 1:04-1:07, 1:20-1:23, 1:44-1:47, 1:52-1:55, and 2:08-2:11.
In this one, Don Everly sings the descending melodic vocals, while brother Phil holds a sustained high E.
This blog is a workshop for developing my analyses of The Beatles' music.