Bay Area composer/performer/media artist Pamela Z is doing a free concert at Brown, one that promises to be witty and heady and actually engaging. A classically trained solo performer, Pamela Z was a pioneer of live looping, processing vocals, percussion, and even breaths to create dense layers of sound. That’s not so uncommon these days – Providence has a whole live looping festival next month – but Pamela Z bought her first vocal processor way back in 1982. These days the loops are triggered by sensors, making each performance a unique visual experience. She’s also renowned as an accessible live performer, which is not always the case with new music or contemporary classical types.