A voice over sydney countertenor is a male singer who can sing as high as a soprano or mezzo-soprano utilizing natural head resonance. Countertenors are extremely hard to come by and their ability to sing as high as C6 is admired by religious music connoisseurs.
Countertenor is the rarest of all voice types.
Though extremely unique, countertenor is not an operatic voice type, as historically, it was the castrati (male singers castrated before puberty) who would be chosen for the female operatic roles – it was not proper for women to sing in the opera. Instead, countertenors were popular in religious choirs, where women were also not allowed to participate.
The castratti are out of the scope of this post, but for those who are interested to learn more about them, I would like to recommend the movie Farinelli, a literary twist on the life of Farinelli, the most famous castrato of all times.