Outkast’s Aquemini (LaFace 73008-26053-2, 74:50) dispels any notion that hip-hop is out of sonic ideas. If anything, it shows that the genre’s appetite for new sounds is as ravenous as ever. On its third album, the Atlanta-based rap duo has effectively raised the ante on not just rap, but funk and R&B-its live-instrument-powered grooves “Slump,” “Aquemini,” “West Savannah” stand head and shoulders above nearly everything on the contemporary pop scene. “Rosa Parks,” which features ’98’s most irresistible chant, takes a break from its acoustic guitar-fueled nod to break into a revival-styled clap along, complete with old-style harmonica. But the fellas really hit their stride near the end of the disc. The languid, “SpottieOttieDoplaiscious” is a dreamy dub-influenced love jam, highlighted by an entrancing spoken narrative and pungent horns. And “Liberation” recalls early Parliament/ Funkadelic at its introspective best-funky choruses cushioned by jazzy rimshots and a floating acoustic piano. Brilliant.