What do remarkably prolific electro-acoustic composers do when they can’t sleep? Wonder no more: Somerville’s own Keith Fullerton Whitman has given listeners a highly welcome window into his own battles with insomnia, and it comes off as one of his most personal works to date.  Greatest Hits, posted for free up to Mr. KFW’s SoundCloud, consists of 12 hours of music, 100 tracks of digitally slowed, chopped, and screwed pop loops from the artist’s youth.  Now, this is way beyond your average “Gaga-slowed-down-times-infinity” YouTube post from xxcharmed1xx.  Whitman is a patient man.  Each clip is treated with the same reverence as an individual memory contained in a thoughtful memoir.  Rather than dwell too deep in a self-designed dungeon, Whitman opens the unknown gates of his pop nostalgia to allow any listener their own entry.  Whitman’s own description is definitely worth reading; below, check out the highlight that begins the third set.