Helicopter Helicopter continue their journey toward pop perfection with this their fourth release. The hand-in-glove vocal harmonies of Chris Zerby and Julie Chadwick are as polished as ever, and most of the power pop is in the form of confident, mid-tempo numbers that, thanks to the relaxed pace, are almost meditative — a departure from the harder-hitting punkish leanings of the band’s past efforts. A few tracks ("Harsh Light," "Time Machine," "1234") recapture the sinister bass lines, surging guitars, and rattling backbeats of Helicopter Helicopter’s grittier days. But in polishing up their rough edges, the band have discovered moodier depths in slow-burners like the piano-backed "The Devil," "Helicopter Fight Song," and the sparse, man-and-his-acoustic-guitar "Pine Trees on Fire." The most noteworthy cut is the finale, "Waves Roll into Boston" — a rebellion against the wave of postmodern pessimism that hangs over so many underground bands these days.