On May 30 1968, The Beatles entered EMI Studio 2 in order to start work on a new LP which would eventually consist of a two record set with the official title "The Beatles" (unofficially known as the "White Album" once released to the public).
The first song to record on the agenda was John Lennon's "Revolution". It would later be changed to "Revolution 1" for the LP version of the tune. The backing track of acoustic guitar, piano and drums would be recorded and take 18 would be chosen as the best backing upon which to overdub. The following day an overdub of John's double tracked vocal , backing "shoo-be-doo-wop" vocals and Paul's bass guitar were added. The whole thing was then reduced to take 19 at this point.
A few days later on June 04 1968 at EMI Studio 3, John continued work on his lead vocals. The high pitched vocal of Paul and George singing "mama...dada" over and over was not used in the end result. Neither was the note of a high pitched guitar feedback loop/ or what sounds like someone going "aaahhh". The whole thing was then reduced to take 20 at this point.
After more overdubbing (Paul on organ and more acoustic guitar); improvisation on the ending of the song with John playing around with the "all right!" vocals and Yoko adding some talking and noises, etc. that would eventually wind up on the LP track "Revolution 9". All of the above taking place before the brass overdubs.
An interesting tape of Yoko rambling into a cassette recorder during the take 20 sessions is available on the bootleg CD "From Kinfauns To Chaos". Take 20 with original overdubs - before they were all chopped off - can be found on the bootleg LP "Revolution" slightly off-speed.
Here is a link to take 20 (running slow) but with the original overdubs intact for your listening pleasure: