Smooth Jazz is an outgrowth of fusion, one that emphasizes its polished side. Generally, smooth jazz relies on rhythms and grooves instead of improvisation. There are layers of synthesizers, lite-funk rhythms, lite-funk bass, elastic guitars, and either trumpets, alto, or soprano saxophones. The music isn't cerebral, like hard bop, nor is it gritty and funky like soul-jazz or groove — it is unobtrusive, slick, and highly polished, where the overall sound matters more than the individual parts