These’ll likely come down soon but, for now, a couple of quick shreds of unreleased Kurt Cobain demos taken from this:
It’s a fan made compilation of Kurt Cobain’s known solo acoustic demos, spoken word pieces and experimental takes. The pieces that I haven’t heard as yet are ‘On a Mission from God’, ‘Speed Ambiance’ plus ‘Intro + Tuning’.
‘Cry Baby Jenkins’ has been around a while – but added to the material on the Montage of Heck soundtrack and the other pieces here, I’m always stunned how underappreciated Cobain’s efforts as a story-teller and writer are. This, like ‘Aberdeen’ or ‘Rhesus Monkey’, show a man interested in the sounds his voice will make, the way he can alter how he pronounces sentences to give different effects – most of what he does in terms of speed, pronunciation, tone, is all deliberate. There’s now enough material available to testify to Cobain’s efforts as a spoken word artist – that in the late Eighties his potential destination wasn’t necessarily Top 40 music stardom, that there were other angles he was pursuing at the same time, multiple directions.
The ‘squeaky voices’ tape manipulation phase – while irksome to many – deserves note. There are now half-a-dozen or more tracks where he’s pursuing this angle. His sister has spoken of how much it entertained Cobain, that this was something that gave him pleasure. It may not be as easily consumed as his verse-chorus-verse guitar work but as a curious diversion, as an aspect that went unseen until recent posthumous releases, it’s interesting to me. ‘When You Are Older’ is as good a name as any for the piece above – and yes, I chuckled at it. There seems to be an audience for it – this is Cobain as entertainer, as someone trying to please people. It’s a warming little sketch of him at ease.
‘Screen’ meanwhile is an early version of ‘Old Age’ with certain lines of lyrics already in place. There’s not much else to note except for his regular tendency to have the structure and melody in place long before the lyrics are pinned.
Nirvana Legacy 
Yeah, ‘Screen’ is basically part of ‘Old Age’. Cobain gave the song to Courtney. She made use of it. There are quite a few demos of Cobain’s work on it now – Cobain didn’t have it finished to his satisfaction by the time of the ‘Nevermind’ sessions in Spring/Summer of 1991. He seems never to have played it live, nor to have developed it further than the end of that year. Check the existing Nirvana archive releases and you’ll find a few editions.