ROCK/POP Elvis Costello - Brutal Youth (Warner Brothers): For music-industry executives who prefer the cloying, sulky tones of singers that sell, sell, sell, Elvis Costello's voice is a marketing nightmare: an angry yelp, a gurgling snarl, with only the occasional smooth, dreamy vocal. But his fans love him anyway. Costello has been reinventing his sound for 18 years now, dabbling in country, big band, and 1960s soul. In this latest effort, Costello brings back his original raw, gnarled sound but this time his lyrics bear the wisdom of a former Angry Young Man. Listen for a touch of Kurt Weill on the rocker ``20 Percent Amnesia'' and revel in the humor of the sweetly cynical ``This is Hell.''