A bass (/ˈbeɪs/ BAYSS) is a type of classical male singing voice and has the lowest vocal range of all voice types. According to The New Grove Dictionary of Opera, a bass is typically classified as having a vocal range extending from around the second E below middle C to the E above middle C (i.e., E2–E4). Its tessitura, or comfortable range, is normally defined by the outermost lines of the bass clef. The bass voice type is generally divided into the basso cantante (singing bass), hoher bass (high bass), jugendlicher bass (juvenile bass), basso buffo ("funny" bass), Schwerer Spielbass (dramatic bass), lyric bass, and dramatic basso profondo (low bass).
Cultural influence and individual variation create a wide variation in range and quality of bass singers. Parts for basses have included notes as low as the B-flat two octaves and a tone below middle C (B♭1), for example in Gustav Mahler's Symphony No. 2 and the Rachmaninov Vespers, A below that in Frederik Magle's symphonic suite Cantabile, G below that (e.g. Measure 76 of Ne otverzhi mene by Pavel Chesnokov) or F below those in Kheruvimskaya pesn (Song of Cherubim) by Krzysztof Penderecki. Many basso profondos have trouble reaching those notes, and the use of them in works by Slavic composers has led to the colloquial term "Russian bass" for an exceptionally deep-ranged basso profondo who can easily sing these notes. Some traditional Russian religious music calls for A2 (110 Hz) drone singing, which is doubled by A1 (55 Hz) in the rare occasion that a choir includes exceptionally gifted singers who can produce this very low human voice pitch.