"John ! Yoko !"

In the afternoon of April 22 1969 John Winston Lennon changed his to John Ono Lennon legally on the roof of the Apple building at 3 Savile Row in London. Once the ceremony was photographed and completed, the couple went along to a recording session at EMI Studio 3 in order to record for their third joint album which would eventually be released commercially as the Apple LP box set "Wedding Album".
The first side of the LP consists of a sensitive microphone picking up the heartbeats of both John and Yoko who were both lying on the studio floor which was recorded for about 20 and a bit minutes. Overdubbed on top of the heartbeats were John saying "Yoko!" and Yoko saying "John !" for 20 and bit minutes. This vocal was pronounced in various emotive tones such as teasing, pleading, inquisitive, yelling, etc.
A first attempt at a stereo mix (with the two voices in the left and right speakers accordingly) and the heartbeats centered. This mix was not used and a second mix on the 26th of that month had a second attempt at a stereo mix.
Finally on April 27 1969 (five days later), the heartbeats had to be re-recorded and it was mixed the same day and released on the commercial Apple LP "Wedding Album" as side one. Pictured above is the Japanese label re-issue on Odeon.