Apokalypsis, Chelsea Wolfe's 2011 LP, ends with several minutes of disconcerting drone. With a spacious mix of hollow tones that may be vocals but may be feedback, too, it's a confusing stretch that closes on a frightened, frightening half-whisper: "What's happening to me?" Wolfe's blend of vulnerability, haunted darkness and animalistic defiance gives her folk-doom the intensity of metal without the need for a crushing mix, or even high volumes. Unknown Rooms: A Collection of Acoustic Songs, due out in October, bears fascinating promise, considering we've already seen the respectable level of anxiety Wolfe can summon with electric timbres. With post-metal sluggers Russian Circles and Marriages. —Corbie Hill