Brown's style of funk was based on interlocking, contrapuntal parts: syncopated basslines, 16th beat drum patterns, and syncopated guitar riffs. The main guitar ostinatos for "Ain't it Funky" (c. late 1960s) are an example of Brown's refinement of New Orleans funk— an irresistibly danceable riff, stripped down to its rhythmic essence. On "Ain't it Funky" the tonal structure is barebones. Brown's innovations led to him and his band becoming the seminal funk act; they also pushed the funk music style further to the forefront with releases such as "Cold Sweat" (1967), "Mother Popcorn" (1969) and "Get Up (I Feel Like Being A) Sex Machine" (1970), discarding even the twelve-bar blues featured in his earlier music. Instead, Brown's music was overlaid with "catchy, anthemic vocals" based on "extensive vamps" in which he also used his voice as "a percussive instrument with frequent rhythmic grunts and with rhythm-section patterns ... West African polyrhythms" – a tradition evident in African-American work songs and chants. Throughout his career, Brown's frenzied vocals, frequently punctuated with screams and grunts, channeled the "ecstatic ambiance of the black church" in a secular context.