Vocalist Jean Smith and guitarist David Lester of Vancouver--known collectively as Mecca Normal--possess a remarkable ability to create symphonic breadth of sound. While their earliest work sounds like angst-ridden sociopolitical folk with a punk edge, their subsequent, more interesting recordings use Smith's voice as an additional instrumental force while Lester's guitar playing exhibits an ever-expansive palette. On last year's Flood Plain (K Records), the pair's individual contributions come together with more depth than ever: Smith's alternately--and sometimes simultaneously--cutting, mewling, piercing, and floating voice conveys a presence at once ethereal and bracing, while Lester's six-string extrapolations are capable of the same stunning range, from delicate arpeggios to crushing blasts of distortion. Smith is a published poet and fiction writer, and her lyrics are oblique but spellbinding, more notable for what they evoke than what they explain. Mecca Normal's leftist politics remain a force, but they've become artfully unobtrusive; on "Current of Agreement," for example, the environmentalism espoused in "Something's blowing / Through the town walls / On a current of agreement / Slowly take the green / From the wood" doesn't overwhelm the inherent musicality, a languid, lush melodicism that slowly insinuates itself into the cranium rather than attacking it. This is the duo's first Chicago appearance since a poorly attended late-80s gig with the Go Team and Some Velvet Sidewalk. Opening are New Zealand's Peter Jefferies (see Critic's Choice) and Trash. Saturday, 10 PM, Lounge Ax, 2438 N. Lincoln; 525-6620.