Pat Metheny is a fusion guitarist of unusual technical gifts, a jazzer with pop instincts and a theoretician prepared to follow his ideas to bizarre conclusions; witness the thrashy cacophony of his 1994 album Zero Tolerance for Silence, an experiment in "flat" music endorsed by Thurston Moore and almost no one else. Metheny's latest release unites the different facets of his musical character, albeit to unsatisfying effect. It's an essay in what he calls "orchestrionics". The idea is that he manipulates live acoustic instruments using a variety of pneumatic contraptions, a hi-tech update of the principles behind the player piano. The album booklet depicts a vibraphone wired up to a battery of pistons, acoustic guitars with robot arms clamped onto them and assorted keyboard and percussion devices. Addressing the natural question "why bother?", the guitarist's introductory essay quotes the inventor Ray Kurzweil: "To extend our reach." Yet the disc sounds very much like a Pat Metheny Band album - one with most of the life removed, at that. Metheny solos over his robot accompanists, his playing light-footed and ingenious, his legato work dazzling as ever. His compositions are poppy and packed with enough strange modal shifts to keep the listener alert, even over five tracks and 50 minutes. They feel like exercises, however, a road test for the new equipment. And only the guitar part could be said to possess charisma. The beds of percussion and keys manage, by contrast, to be superhumanly intricate without generating any interest. It's tempting to say back to the drawing board, but at this stage, Metheny might take it literally.