A bass (/beɪs/ BAYSS 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).^[1] Its tessitura, or comfortable range, is normally defined by the outermost lines of the bass clef. Categories of bass voices vary according to national style and classification system. Italians favour subdividing basses into the basso cantante (singing bass), basso buffo ("funny" bass), or the dramatic basso profondo (low bass). The American system^[2] identifies the bass-baritone, comic bass, lyric bass, and dramatic bass. The German fach system^[3] offers further distinctions: Spielbass (Bassbuffo), Schwerer Spielbass (Schwerer Bassbuffo), Charakterbass (Bassbariton), and Seriöser Bass. These classification systems can overlap. Rare is the performer who embodies a single fach without also touching repertoire from another category.

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's All-Night Vigil, 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.

Many British composers such as Benjamin Britten have written parts for bass (such as the first movement of his choral work Rejoice in the Lamb) that center far higher than the bass tessitura as implied by the clef.^[1] The Harvard Dictionary of Music defines the range as being from the E below low C to middle C (i.e. E2–C4).^[4]

The bass has the lowest vocal range of all voice types, with the lowest tessitura. The low extreme for basses is generally C2 (two Cs below middle C). However, some extreme bass singers, referred to as basso profondos and oktavists, are able to reach much lower than this.

In SATB four-part mixed chorus, the bass is the lowest vocal range, below the tenor, alto, and soprano. Voices are subdivided into first bass and second bass with no distinction being made between bass and baritone voices, in contrast to the three-fold (tenor–baritone–bass) categorization of solo voices. The exception is in arrangements for male choir (TTBB) and barbershop quartets (TLBB), which sometimes label the lowest two parts baritone and bass.

Within opera, the lowest note in the standard bass repertoire is D2, sung by the character Osmin in Mozart's Die Entführung aus dem Serail, but few roles fall below F2. Although Osmin's note is the lowest 'demanded' in the operatic repertoire, lower notes are heard, both written and unwritten: for example, it is traditional for basses to interpolate a low C in the duet "Ich gehe doch rathe ich dir" in the same opera; in Richard Strauss' Der Rosenkavalier, Baron Ochs has an optional C2 ("Mein lieber Hippolyte"). The high extreme: a few bass roles in the standard repertoire call for a high F♯, the one above middle C), but few roles go over F4. In the operatic bass repertoire, the highest notes are a G♯4 (The Barber in The Nose by Shostakovich) and, in the aria "Fra l'ombre e gl'orrori" in Handel's serenata Aci, Galatea e Polifemo

Within the bass voice type category are seven generally recognized subcategories: 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).

Basso cantante means "singing bass".^[5] Basso cantante is a higher, more lyrical voice. It is produced using a more Italianate vocal production, and possesses a faster vibrato, than its closest Germanic/Anglo-Saxon equivalent, the bass-baritone.

Hoher Bass or "high bass" or often a dramatic bass-baritone.

Jugendlicher Bass (juvenile bass) denotes the role of a young man sung by a bass, regardless of the age of the singer.

Buffo, literally "funny", basses are lyrical roles that demand from their practitioners a solid coloratura technique, a capacity for patter singing and ripe tonal qualities if they are to be brought off to maximum effect. They are usually the blustering antagonist of the hero/heroine or the comic-relief fool in bel canto operas.

English equivalent: dramatic bass

Basso profondo (lyric low bass) is the lowest bass voice type. According to J. B. Steane in Voices, Singers & Critics, the basso profondo voice "derives from a method of tone-production that eliminates the more Italian quick vibrato. In its place is a kind of tonal solidity, a wall-like front, which may nevertheless prove susceptible to the other kind of vibrato, the slow beat or dreaded wobble."

English equivalent: dramatic low bass.

Dramatic basso profondo is a powerful basso profondo voice.

All of the Gilbert and Sullivan Savoy operas, except Patience and The Yeomen of the Guard