There are, of course, no more castrati, male singers castrated in their youth so as to preserve their high, immature voices. And while no one would ever suggest a return to the barbaric practice, music historians have long lamented the loss of the unique sound such performers produced. In the last century, the parts originally written for castrati have been largely sung by countertenors, men singing in highly developed falsetto. But many of the most difficult Baroque castrato operas have been all but abandoned for lack of skilled enough performers in the countertenor range. Until now.