Known as "Sgt. Pepper Inner Groove", the concentric run-out groove on UK copies of the Parlophone UK "Sgt. Pepper's Lonely Hearts Club Band" contains a spoken message of gibberish recorded by The Beatles on Friday April 21 1967 at EMI Studio two. At the recording stage it was known as "Edit For LP End". This consisted of noise, talking, etc by filling up two tracks of nonsense and editing it down to the length of the groove ( 3 seconds ) heard on the vinyl record ( and at the end of the CD). The vinyl record only contains the one groove playing over and over again until the stylus of your record player was lifted. If the record player was automatic, only a short burst of the groove would be heard before the needle lifted off the record. The CD contains the recording being heard over and over until it fades out.
There is also a 15 kilocycle high pitch noise heard between the end of "A Day In The Life" and the "Inner Groove" that was produced during the cutting of the mono and stereo copies of "Sgt. Pepper" . This was added at EMI studios in the cutting room by Harry Moss. The mono copy was cut on April 28 1967 and the stereo copy was cut on May 01 1967. It's been said that if you play the inner groove backwards, a nasty message is produced.
The 15 kilocycle frequency and the "Inner Groove" are available on the Parlophone UK LP/CD "Sgt. Pepper's Lonely Hearts Club Band" on the mono and stereo version. The North American Capitol LP of the same name does NOT have either the high frequency nor does it contain the "Inner Groove". This item was subsequently available on the North American Capitol LP "Rarities".