With such songs as “God Smack” and “Hate to Feel” crammed thick with junkie rage and Oedipal tension, Dirt (1992) is the musical equivalent of coughing blood — harrowing and real. Dense guitars spin ominous, flattened melodies: the sound of cages rattling. Acoustic leaning, the new seven-song EP from the Seattle quartet Alice in Chains is subtler — strings lighten “I Stay Away,” and “Whale and Wasp,” an instrumental, is darkly gorgeous. On “Swing on This” and “Rotten Apple,” Layne Staley’s vocals, owing as much to Styx and Kansas as Jerry Cantrell’s guitars do to Black Sabbath, evoke pathos as well as anger. Yet this is hardly Alice lite. “I repent tomorrow,” Staley sings, wary even of hope, and in nearly every song, the word home wrenchingly resounds — an ache, a bitter prayer.