Entrevista com Ken Scott...

... que foi engenheiro de som de algumas gravações dos Beatles:

https://audiophilestyle.com/ca/the-interview-series/the-interview-series-ken-scott-r936/

2012-04-30: Ken Scott fala de gravações com os Beatles (White Album)

http://www.guitarworld.com/interviews/abbey-road-engineer-ken-scott-beatles-white-album-sessions-were-blast/15536

Citando:
"What can you tell me about the session for "While My Guitar Gently Weeps," when Eric Clapton came in to play the guitar solo?
That's a question I'm asked so frequently, and I have absolutely no recollection of it whatsoever. For the book, I wanted to try and get back to that session because I know it's a very important session and a lot of people are interested in it. I actually tried regression therapy to take me back, and, unfortunately, it didn't work [laughs]. I still have no memory of that session.

Given the song's heaviness, was there anything special about the “Helter Skelter” session?
Not much different—they just played a lot louder than usual."