Vocal type

A voice type is a particular human singing voice identified as having certain qualities or characteristics of vocal range, vocal weight, tessitura, vocal timbre, and vocal transition points (passaggio), such as breaks and lifts within the voice. Other considerations are physical characteristics, speech level, scientific testing, and vocal register. A singer's voice type is identified by a process known as voice classification, by which the human voice is evaluated and thereby designated into a particular voice type. The discipline of voice classification developed within European classical music and is not generally applicable to other forms of singing. Voice classification is often used within opera to associate possible roles with potential voices. Several different voice classification systems are available to identify voice types, including the German Fach system and the choral music system among many others; no system is universally applied or accepted.

Voice classification is a tool for singers, composers, venues, and listeners to categorize vocal properties and to associate roles with voices. While useful, voice classification systems have been used too rigidly, i.e. a house assigning a singer to a specific type and only casting him or her in roles they consider belonging to this category. While choral singers are classified into voice parts based on their vocal range, solo singers are classified into voice types based more on their tessitura – where their voice feels most comfortable for the majority of the time.

A singer will choose a repertoire that suits his or her instrument. Some singers such as Enrico Caruso, Rosa Ponselle, Joan Sutherland, Maria Callas, Ewa Podleś, or Plácido Domingo have voices that allow them to sing roles from a wide variety of types; some singers such as Shirley Verrett or Grace Bumbry change type and even voice part over their careers; and some singers such as Leonie Rysanek have voices that lower with age, causing them to cycle through types over their careers. Some roles as well are hard to classify, having very unusual vocal requirements; Mozart wrote many of his roles for specific singers who often had remarkable voices, and some of Verdi's early works make extreme demands on his singers.

...
Wikipedia