'EVOL' was a major leap forward for Sonic Youth, but 'Sister' is a masterpiece, demonstrating the group's rapidly evolving musicality. More than ever before, Sonic Youth's songs sound like actual songs, and their collages of noise, distortion, and alternate tunings are now used to provide texture and depth to the music, which is original, complex, and rewarding. Not only is there the full-throttle roar of 'Tuff Gnarl,' but there are shimmering layers of ambient harmonics and dissonance that are as haunting and challenging as any of their barrages of feedback. Furthermore, 'Sister' has a warm sound, which lures the listeners into music that's defiantly arty but never indulgent.