For a tiny segment of the world's music lovers, drones are as essential as oxygen. While many find this minimal, seemingly static style somnolent, true drone-oisseurs exalt it as the ultimate expression of sonic transcendence. Gregg Kowalsky proved his mettle with 2006's Through the Cardial Window, a nutritious aural soup of guitar, violin, melodica, and field recordings. With this year's Tape Chants, Kowalsky feeds the sounds of shruti box, gongs, and percussion through a cassette recorder, forging intimate, whorling sine-wave symphonies. It's pure bliss. (Josephine, 608 NW 65th St, www.myspace.com/thejosephine. 9 pm.)