Tortoise revolutionized American indie rock in the mid-'90s by playing down tried-and-true punk and rock & roll influences, emphasizing instead the incorporation of a variety of left-field music genres from the previous 20 years, including Krautrock, dub, avant-garde jazz, classical minimalism, ambient and space music, film music, and British electronica. At odds as well with the shambling framework of alternative rock's normal song structure, the group -- as large as a septet, with at times two vibes players -- relied on a crisp instrumental aesthetic, tied to cool jazz, whic...