 Ghosts I – IV is an almost entirely instrumental album , with only a few tracks containing sampled vocals . Reznor described the album 's sound as " the result of working from a very visual perspective — dressing imagined locations and scenarios with sound and texture ; a soundtrack for daydreams . " PopMatters ' review of the album compared its musical style to that of Brian Eno and Robert Fripp , ultimately categorizing it as " dark ambient " . The review went on to describe the music as " a tonal painting , a collection of moods and not all of these moods are good ones . " National Public Radio compared the album to the music of Erik Satie and Brian Eno ; Rolling Stone 's review to Brian Eno , specifically the album 's sound to the instrumentals of Another Green World ( 1975 ) and the rhythm collages of My Life in the Bush of Ghosts ( 1981 ) . Robert Christgau also compared the album to the work of Brian Eno , summarizing Ghosts ' sound as " mental wallpaper " . 
