When fans describe 'The Wire,' no adjective seems to surface as often as "gritty." After five seasons, creator David Simon's painstaking arrangement of granular bits of research and authenticity, whether the detectives' banter or Snoop's drawl, have added up to a tone as low key and abrasive as the real Baltimore.

For writers, costume designers and prop masters, mimicking reality falls into the standard job description, but music supervisor Blake Leyh - who, on another show, might compose sweeping themes and clever montages - has to fight the instinct to draw sentimental connections through song choice. "I want to make the scene less emotional, less melodramatic," he says. "We put music in there as a device to push you away from the people a little bit. It's something you would so rarely do in a Hollywood movie; you would want to pump up the emotion. But on 'The Wire,' so often we're trying to go against that."

As a rule, almost every song on the show emanates from an on-screen source like a radio or jukebox, so Leyh has developed an anthropological approach to his work, leafing through the scripts searching for speakers and then deducing what would drift out of them. "The first thing that music is doing, rather than highlighting emotion, it's creating a sense of place," he says. "If it's a scene with Michael's crew standing on the corner, we need hip-hop to go in there. The range of cues that would work is so wide that it starts to become more about the real-world context of that music, so I'm turning to the music that kids in Baltimore are listening to." Or the cops, the union bosses, the teachers or anyone else in Simon's reflection of Baltimore.

To speed the process along, Leyh habitually collects songs, noting the music he hears near his Harlem studio and tucking it away for future use. "I'm all the time just out in the world thinking about music," he says. "If I hear a song out in the real world two or three times, I'll go online, figure out what that song is and try to clear the rights." He enjoys the challenge of puzzling through the creative limitations - conventions so exacting that he'll literally shift a song forward by a quarter of a second so it doesn't begin too cleanly on a musical phrase. Leyh began his tenure on 'The Wire' composing about a dozen original songs, trying to capture the spirit of Simon's vision. Only the closing-credit piece, 'The Fall,' ever appeared on the show. "David didn't like any of them," he says. "It's such a huge journey that has taken place since then. I can look back now, and I can say that I didn't understand what 'The Wire' was about."