A soprano is a voice type with a vocal range (using scientific pitch notation, where middle C = C4) from approximately middle C (C4) to “high A” (A5) in choral music, or to “soprano C” (C6, two octaves above middle C) or higher inoperatic music. In four-part chorale style harmony, the soprano takes the highest part, which usually encompasses the melody. In choral music, the term soprano refers to a vocal part or line and not a voice type. Male singers whose voices have not yet changed and are singing the soprano line are technically known as “trebles”. The term “boy soprano” is often used as well.
The musical term alto, meaning “high” in Italian (Latin: altus), refers to the second highest part of a contrapuntal musical texture and is also applied to its associated vocal range, especially in choral music. More rarely it describes the highest male solo voice type (usually designated countertenor), the lowest standard female voice type. When designating instruments, “alto” likewise can refer either to the corresponding vocal range of F4-F6 and G2-B♭5).
The tenor is a type of male singing voice and is the highest male voice within the modal register. The typical tenor voice lies between C3, the C one octave below middle C, to the A above middle C (A4) in choral music, and up to high C (C5) in solo work. The low extreme for tenors is roughly B♭2 (two B♭s below middle C). At the highest extreme, some tenors can sing up to two Fs above middle C (F5). In four-part choral music, the tenor is the second lowest voice, above the bass and below the soprano and alto. While certain choral music does require the first tenors to ascend the full tenor range, the majority of choral music places the tenors in the range from approximately B2up to A4. The requirements of the tenor voice in choral music are also tied to the style of music most often performed by a given choir
A bass is a type of male singing voice and possesses the lowest vocal range of all voice types. a bass is typically classified as having a 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. In choral music, voices are subdivided into first bass and second bass, 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.