The bass-baritone voice is distinguished by two attributes. First, it must be capable of singing comfortably in a baritonal tessitura. Secondly, however, it needs to have the ripely resonant lower range typically associated with the bass voice. For example, the role of Wotan in Die Walküre covers the range from F2 (the F at the bottom of the bass clef) to F♯4 (the F♯ above middle C), but only infrequently descends beyond C3 (the C below middle C). Bass-baritones are typically divided into two separate categories: lyric bass-baritone and dramatic bass-baritone.
Bass-baritones should not be confused with their vocal cousin—the so-called Verdi baritone. This type of Italianate baritone voice has a brighter tone colour and sings at a slightly higher tessitura than that possessed by the bass-baritone. In addition to the operas of Giuseppe Verdi, its natural home is to be found in operatic music composed after about 1830 by the likes of Donizetti, Ponchielli, Massenet, Puccini and the verismo composers.
The term bass-baritone is roughly synonymous with the Italian vocal classification basso cantante; for example, in the Verdian repertoire, Philip II in Don Carlos is often taken by a bass-baritone, while Ferrando in Il trovatore is sung by a true bass—though the two roles' ranges are very similar. In Debussy's Pelléas et Mélisande the lower baritone role of Golaud is a bass-baritone, sitting between Pelleas (high baritone) and Arkel (bass). (See under fach for more information.) Much of the oratorio repertoire, from Handel's Messiah to Mendelssohn's Elijah, is best suited to a bass-baritone with the ability to combine a rich, dark tone with a smooth, high-lying cantabile line. Some of the classical Mozart baritone roles such as Don Giovanni, Figaro and Gugliemo—composed before the term "baritone" gained currency—are occasionally played by a bass-baritone.
In short: the bass-baritone is a voice that has the resonant low notes of the typical bass allied with the ability to sing in a baritonal tessitura. Colloquially, it refers to a voice with a range and tone somewhere between a bass and a baritone.
The bass-baritone's required range can vary tremendously based on the role, with some less demanding than others. Many bass-baritones have ventured into the baritone repertoire, including (among others) Leopold Demuth, George Baklanov, Rudolf Bockelmann, George London, James Morris and Bryn Terfel.
The following operatic parts are performed by bass-baritones but sometimes by high basses: