It's difficult to discern whether Geoff Leigh and Yumi Hara are improvising freely, or if they've pre-composed the pieces on their Upstream collaboration. Although a multi-instrumentalist, Leigh concentrates mainly on the flute, although it's frequently fed through an entanglement of electronic effects, lending a subtly harmonized burr. Hara plays keyboards, changing her palette from acoustic piano to hard-edged organ sounds. Their music possesses some highly contrasting densities. Leigh coats his small gongs with an effects burnish, spangling into infinity. Hara also alters her voice at times, again with a subtly harmonized displacement.