"... his voice develops a range, power and flexibility quite different from the singing voice of the adult female, but also markedly different from the higher vocal ranges of the uncastrated adult male. Some castratos were males who were born with an endoctrinological condition that prevented them from sexually maturing."
The term castrato was often used to indicate the high register created by the young men who sang the castrato style. The typical register of a castrato was above that of a 'normal' soprano or alto voice, resulting in the creation of a temporary range in Italian music." 4
In Italy, where most of the castrations occurred, boys were generally drugged with opium. They were soaked in a hot tub until barely conscious before the operation. 5 One source estimates that the fatality rate due to the amputation procedure was about 80%. 6 Another estimates a death rate of 10 to 80% depending upon the skill of the practitioner. 7 Among the survivors, the vast majority did not become professional singers because their voice was not of sufficiently high quality.
J.S. Jenkins writes:
"Boys were castrated between the ages of 7 and 9 years, and underwent a long period of voice training. A small number became international opera stars, of whom the most famous was Farinelli, whose voice ranged over three octaves. By the end of the 18th century, fashions in opera had changed so that the castrati declined except in the Vatican, where the Sistine Chapel continued to employ castrati until 1903. The last of the castrati was Alessandro Moreschi, who died in 1924 and made gramophone recordings that provide the only direct evidence of a castrato's singing voice." 8
Obviously, all of the boys who were castrated were not sufficiently mature to give their informed consent.History:
The European practice of employing castrated boys in the Catholic church's choirs started in the mid 16th century.
Pope Sixtus V issued a papal Bull in 1589 which approved the recruitment of castrati for the choir of St. Peter's Basilica in Rome. Castrati were later widely employed by opera companies.
According to Wikipedia:
"The practice reached its peak in 17th and 18th century opera. In Naples it is said that several barbershops had a sign that castration was performed there. However, this cannot be confirmed. The male heroic lead would often be written for a castrato singer (in the operas of Handel for example). When such operas are performed today, a woman (possibly cross-dressing as a man in a so-called trouser role) or a countertenor takes these roles. However, some Baroque operas with parts for castrati are so complex and difficult that they cannot be performed today."
"Castration was by no means a guarantee of a promising career. During the 16th, 17th and 18th centuries, only approximately 1% of fully or partially castrated boys developed into successful singers."
"Probably the most famous castrato was the 18th century singer Carlo Broschi, known as Farinelli. In 1994, a film was made about him, Farinelli Il Castrato. In the 17th century, Queen Christina of Sweden was so enamored of the voices of the castrati that she temporarily halted a war between her country and Poland so that she could borrow the castrato Ferri from the Polish king for a two-week command performance." 4
According to Rotten.com, in the late 16th century,
"Pope Clement VIII became smitten with the sweetness and flexibility of their voices. ... While some Church officials suggested it would be preferable to lift the ban on women singers than to continue endorsing the castration of little boys, the Pope disagreed, quoting Saint Paul, 'Let women be silent in the assemblies, for it is not permitted to them to speak.' ... since it was illegal to perform castrations, ... all castrati presenting themselves for the choir claimed to have lost their genitals through tragic 'accident'."
"After the Pope’s official acknowledgement and acceptance of castrati, the number of these "accidents" increased dramatically. Parents seeking upward mobility towed their little lads down to a barber or butcher who separated them from their testicles for a fee.
One source estimates that, during the 17th and 18th centuries, three to five thousand boys per year in Italy were castrated . Castration was forbidden under canon law. The church condemned the practice and occasionally excommunicated the person responsible for the surgery. 6 But the church simultaneously created a market for castrati by hiring them for its church choirs. By about 1789, there were more than 200 castrati in Rome's chapel choirs alone.
The number of castrati declined during the 19th century. In 1870, castrations were banned in the Papal States -- the last political jurisdiction to do so. In 1878, Pope Leo XIII prohibited the hiring of new castrati by the church.
By 1900 there were only 16 castrati singing in the Sistine Chapel and other Catholic choirs in Europe. In 1902, Pope Leo XIII ruled that new castrati would not be admitted to the Sistine Chapel.
In 1903, Pope Pius X formally banned adult male sopranos from the Vatican. Roman Catholicism's last castrati, Alessandro Moreschi, died in 1922.