Layering spacey sound effects astronaut chatter, air-raid sirens, elephant flatulence over a funky techno beat, this British ''ambient house'' band's second full-length album, u.f.orb, takes us to dark sides of the moon Pink Floyd never dreamed of. It's not exactly toe-tapping Top 40 material, but the Orb's sound is hypnotic and often spookily beautiful. A

