Virtuosity was shown by mercurial agility, changes in register and tessitura, perfect control of dynamics and tonal coloration, not by whistle-like high notes.
For contraltos on the other hand, they started to be more used in Rossini's bel canto operas for example, and to assume roles replacing the castrati who by that time were almost extinct, and composers demanded a range often going as high as B5.
The term soprano sfogato appeared in the bel canto era of the 19th century, the time when its greatest exponents were performing.
Other roles associated with this voice type are Elisabetta in Roberto Devereux, Gemma di Vergy, Reiza in Carl Maria von Weber's Oberon.
The common requirements for the roles associated with this voice type are: The major exponents of the soprano sfogato vocal type were able to sing both soprano and contralto roles: Giuseppina Ronzi de Begnis was the first Elisabetta in Devereux, and she also performed Bellini's Romeo as well as Norma; Isabella Colbran sang both Armida and Desdemona in Rossini's Otello as well as the contralto role of Paisiello's Nina and Mozart's soprano heroines; Giuditta Pasta originated Anna Bolena, Norma and La Sonnambula as well as singing Cenerentola, Tancredi, Arsace, Cherubino and Romeo.