“Castrato: "A castrato is a man with a singing voice equivalent to that of a soprano, mezzo-soprano, or contralto voice produced either by castration of the singer before puberty or one who, because of an endocrinological condition, never reaches sexual maturity."

Castration before puberty (or in its early stages) prevents a boy's larynx from being transformed by the normal physiological events of puberty. Thus, vocal range of prepubescence is largely retained, and the voice develops into adulthood in a unique way.
As the Castrato's body grows, his lack of testosterone means that his bone-joints do not harden in the normal manner. Unusually long ribs, combined with intensive training, gave them unrivaled lung-power and breath capacity. Operating through small, child-sized vocal cords, their voices were also extraordinarily flexible, and quite different from the equivalent adult female voice, as well as higher vocal ranges of the un-castrated adult male. Listening to a castrato, one can hear that the lower part of the voice sounds like a "super-high" tenor, with a more falsetto-like upper register above that.
Prepubescent castration was made illegal in Italy in 1870.

---

Some famous Castrati

1. Baldassare Ferri
2. Giovanni Carestini
3. Alessandro Moreschi”