The Rolling Stones - 'Quiet Here At Home' aka 'Hear It'
Recorded at RCA Victor Recording Studios, 6363 Sunset Boulevard, Los Angeles, California, USA. 3rd - 11th August 1966.

Brian and/or Keith - acoustic guitars? What do you think?
Strings etc - session musicians - possibly recorded at a later date.

Full mix:




Left speaker:




Right speaker:




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Here is what collector, Matt Lee has to say about this track and the related acetate in his excellent book 'Rolling Stones - Hot Stuff: The Ultimate Memorabilia Collection'.

"Quiet Here At Home' Acetate:
After "discovering" the Mick Jagger - Carly Simon duet in 2018 on a tape I had stored away, I thought I had found an unreleased and uncirculated Rolling Stones single from the 1960's. Unfortunately, the song entitled 'Quiet Here At Home' on an acetate I acquired several years before had already been in circulation among fans, but under the name 'Hear It'. The song has no lyrics, which is probably why there is a discrepancy.
The acetate has several songs that were recorded during the sessions in 1966 for the album Between The Buttons, including 'Trouble In Mind', an old blues song written by jazz artist Richard. M Jones. The thing that makes that song interesting is the kazoo playing throughout, believed to be by Brian Jones, Mick Jagger and Keith Richards.
On the acetate, the second side features two tracks with kazoo improvisation, making it a fascinating but strange listening experience. The acetate misidentifies the song 'Trouble In Mind' as 'Avant Garde', which is odd as someone calls out the correct name at the end of the song in a few moments of studio chatter.
The not-so-lost single, listed by the longer name of 'It's Been Quiet Here At Home' on many websites, was on side one along with 'Miss Amanda Jones', 'Something Happened To Me Yesterday' and 'Who's Been Sleeping Here' - all three of which were eventually released on Between The Buttons."

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With thanks to Matt Lee for the acetate information and to Nico Zentgraf for the recording session dates.

A photo from the session perhaps?

RCA Victor Recording Studios, 6363 Sunset Boulevard, Los Angeles, California, USA. 3rd - 11th August 1966 - by Ian Stewart.

Heavy touch on the strings and bass notes runs sound like could be Keith, strumming pattern not much so. Just a guess!

C

My guess would be that both guitars are Keith. However, it's not impossible that the guitar in the left channel is Brian. They are suspiciously alike, though.

Indeed they are. I do think both are by Keith.

But, keeping an open mind of a scenario something like a post tour, pre hand injury Brian perhaps having a good day playing with Keith.