I struggle a little bit with the concept of a piece which you can't quite hear as too many years of sitting in front of the percussion section in orchestras has had it's toll on my eardrums. Personally, I like my music to be of a volume that I can actually hear it.
But it's always good to push the boundaries and open a debate about music.
Martino Panizza (harp) and Alice Purton (cello)
Charlie Sdraulig, hush (2011-12)
Score available here: http://www.charliesdraulig.com/hush.pdf
More about the notation: http://johnsonsrambler.wordpress.com/2012/04/16/the-contemporary-notation-project/
Engineer: Erik Nyström
N.B. This work is extremely soft. Where possible, try to listen to this piece in a quiet environment on a good set of speakers or with headphones.
Studio recording: http://soundcloud.com/charlie-sdraulig/hush