Known as the highest natural male voice, tenors sing above the melody, complementing the lower voices with a developed, mature sound. Tenors sing without much vibrato, the tremulous effect produced when a note is sustained.
The four categories of tenor voices include the countertenor, lyric tenor, dramatic tenor and choir tenor. Countertenors convey a clean and clear tone. Lyric tenors must be more flexible to allow the voice a smoother transition between registers. Dramatic tenors are capable of great authority and staying power, which makes them suitable for grander musical works. Choir tenors lack the power of lyric tenors and closely resemble baritone voices to the extent that they are often referred to as light baritones.
The lead vocalist sings the melody with precision, stability and power. The lead's voice projects the emotion of the song while the tenor, baritone and bass provide vocal support. Lead vocalists tend to have wide vocal range and can sing between its extremes.
Sung either above or below the melody, the baritone voice must convey considerable depth to fill the distance between the lead and bass voices. The baritone also sings within the same vocal range as the lead.
Baritone voices can be divided into lyric baritones, dramatic baritones, bass baritones and choir baritones. Lyric baritones are the most frequently performed vocal type in musical theater productions. By exuding a soft tone, lyric baritones harmonize well with tenor voices. Dramatic baritones are the most flexible of the baritones and are well-suited to abrupt shifts. Bass baritones possess a deeper range and darker tonality when compared to the other baritones.
Known as the lowest note in a quartet, the bass sings from the lower register and with minimum vibrato, providing the foundation for the quartet's vocal harmony. Bass vocalists sing in harmony with lead vocalists.
Voices that fall into the bass category can be further subdivided into bass cantante, bass profundo and choir bass. Best suited for sustained passages, bass cantante voices are rare, yet flexible, unlike bass profundo voices that lack similar variability. Choir bass performances are more common in amateur vocal groups and signify untrained voices.