Putting any kind of music on for solo listening is in some way an act of shutting out the world...I'm not sure if I have anything I go for in order to feel especially isolated or shut out.  But, on rare and specific occasions - usually late at night - where I'm feeling pleasantly quiet and solitary (i.e. no noise coming from room mates, neighbours, etc) I find long form, minimal improvisation is a lot of fun.  Ultra lower case EAI type shit or very minimal drone.  Young, Conrad etc.  Beautiful times.