When Pitchfork invited electronic composer Keith Fullerton Whitman to initiate us into the mysteries of ambient music a few years back, he asked , “What music isn’t ambient in the 21st century?” He meant it rhetorically, as an observation about listeners’ increasingly imperiled attention spans. All music these days, from the three-minute pop song to the IMAX-juiced film score, is by default “ as ignorable as it is interesting ,” as Brian Eno’s famous formulation goes. But in a year in which