In Celebration of the Human Voice - The Essential Musical Instrument
The name "tenor" derives from the Latin word tenere, which means "to hold". In medieval and Renaissance polyphony between about 1250 and 1500, the tenor was the structurally fundamental (or holding) voice, vocal or instrumental. All other voices were normally calculated in relation to the tenor, which often proceeded in longer note values and carried a borrowed Cantus firmus melody. Until the late 15th-century introduction of the contratenor bassus, the tenor was usually the lowest voice, assuming the role of providing a harmonic foundation. It was also in the 15th century that "tenor" came to signify the male voice that sang such parts. Thus, for earlier repertoire, a line marked 'tenor' indicated the part's role, and not the required voice type. Indeed, even as late as the seventeenth century, partbooks labelled 'tenor' might contain parts for a range of voice types. In four-part choral music, the tenor is the second lowest voice, above the bass and below the soprano and alto. The range of the choral tenor is generally not as great as that in opera, however.
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 B2 up to G4. The requirements of the tenor voice in choral music is also tied to the style of music most often performed by a given choir. Orchestra choruses require tenors with fully resonant voices, but chamber or a cappella style choral music can quite successfully rely on light baritones singing in the falsetto. Although vocal range is the primary characteristic which defines a tenor, it is not the only. A tenor is ultimately classified by several vocal traits, including range, tone quality, vocal lift points, and transition points ("passaggio") within the singer's range. It is generally recognized that the average transitional area, or passaggio, of the tenor begins with a lift around middle C or C# and ends with a lift at F or F# above that (Alderson 1979). In non-professional choirs, individuals will generally be classified based on their most resonant and comfortable tessitura. In the Barbershop harmony musical style, the name "tenor" is used for the highest part. The four parts are known (lowest to highest) as bass, baritone, lead, and tenor. The tenor generally sings in falsetto voice (thus the term tenor used in barbershop terminology most closely corresponds to the term countertenor as used in classical music), and harmonizes above the lead, who sings the melody. The barbershop tenor range is, as notated, Bb-below-middle C to D-above-high-C (and sung an octave lower)