Farewell Symphony was originally written for Round One of the 2009 Whittaker Prize. The prompt used was a picture of a derelict shack. It was given a score of 77/100 by the judge, Geoff Nelder, putting it in second place out of 30.
I read a mildly-edited version of Farewell Symphony at Tales of the Decongested in London on April 24th, 2009. I think I may have gabbled a bit.
There was always something that was nagging me about this story, and I finally fixed it just after Dot Dash had been accepted for publication. All I needed to do was remove the last sentence:
But it had taken Paavo ten years to work out how to tell us all.
which wasn't adding any value whatsoever.
As for what kind of thing Paavo had been composing, well, it probably couldn't actually exist. However, I think Rautavaara's Cantus Arcticus is about as close as you're likely to get.