The Art of Fugue
"SATB" can to also refer to ensembles of four instruments from the same family, such as saxophones (soprano, alto, tenor and baritone) or recorders. Individual contrapuntal parts of many instrumental compositions, particularly fugues, such as those found in Bach's "The Art of Fugue" and "The Musical Offering", may also be called "SATB" without implying any correlation with vocal ranges.