Voice type is a particular kind of singing voice which has identifable qualities or characteristics. Voice classification is where human voices are evaluated and designated into voice types. These qualities include vocal range, weight, tessitura, timbre and transition points.Voice classification is not only a tool for singers and composers, but it also helps venues and listeners to categorize vocal properties, and to associate possible roles with potential voices. A singer will ultimately choose a repertoire with which they feel comfortable. Some singers such as Joan Sutherland, Maria Callas, Ewa Podles, or Plácido Domingo have voices which allow them to sing roles from a wide variety of types; other singers, such as Shirley Verrett or Grace Bumbry, change type over their careers. Some singers, Alfredo Kraus for example, choose to stick religiously to their voice type and yet other singers, such as Leonie Rysanek, have voices which lower with age.
Source: http://en.wikipedia.org/wiki/Voice_types
Image: His Master's Voice. www.flickr.com
