Terminology
"Contralto" is meaningful only in reference to classical and operatic singing, as other genres lack a system of vocal categorization comparable to that generally accepted in the classical context. Even within current operatic practice, contraltos are often classed as mezzo-sopranos, because singers in each range can cover for those in the other. When appearing separately, the term "contralto" applies only to female singers; men whose voices fall in the same range or higher are known as "countertenors." The Italian terms "contralto" and "alto" are not synonymous, the latter technically denoting a specific vocal range in choral singing without regard to factors like tessitura, vocal timbre, vocal facility, and vocal weight.
Within the category of contraltos are three generally recognized subcategories—coloratura contralto, lyric contralto, and dramatic contralto—that usefully describe the voice type in general terms. Note, however, that they do not always apply with precision to individual singers; some exceptional dramatic contraltos, such as Ernestine Schumann-Heink and Sigrid Onégin, were technically equipped to perform not only heavy, dramatic music by the likes of Wagner but also florid compositions by Donizetti.
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