Entirely free of context, the music that Volker Bertelmann produces under the Hauschka moniker might not be all that impressive to an electronic music fan. The German musician grew up studying classical piano, and he followed that up by forming a hip-hop duo with his cousin. That intersection isn’t exactly new ground — Hauschka’s strongest compositions range up near the high-rises established there before him. But then again, it would be easy to assume that his songs were layered with synth, strings, and percussion, the standard tools to produce an album of wet-gray instrumentals reminiscent of urban decay. But on Abandoned City, Bertelmann uses only a “prepared” acoustic piano, filtered through reverb and distortion.