I recently heard Handel's Messiah performed with 'original instruments' here in Manhattan. Well, not actually. The instruments were modern while the strings were made of gut rather than steel. What annoyed the hell out of me, however, was not the manner in which the orchestra played, but rather, the manner in which the soloists sang; all of them it seems, were instructed to start with straight tone, and then let the voice vibrate. Here's why this approach is misinformed and wrong when applied to the music of Handel.
Handel wrote for singers trained in bel canto: that being a freely vibrating voice from start to finish. To straighten the tone and then let it vibrate - say - at the start of the tenor's aria Comfort Ye, betrays a lack of knowledge in how messa di voce is done. The bel canto singer is trained to keep the same timbre when going from mezza voce to mezzo forte singing, not hold the larynx as straight tone is imposed, which fixes the vocal tube and destroys the twin sensations of open throat and placement.
Bel canto tone is agile, free and full: three essential requirements, no matter what dynamic is sung. To fix the larynx when singing quietly, then let it go when volume is increased is jarring to the ear, and anything but free and full (no, I did not write dark and wobbly). More than one singer did this when launching into a flourish of fioritura after strangling the tone. Not beautiful!
Why is this so hard for conductors to understand? Do they not listen? No. They do not, since, by-and-large, they cannot trill or execute a fine messa di voce, both of which require an ear for pure vowels. Many conductors today, unfortunately, have little idea of what this means. They think rather than do.
If you are going to tell a singer to drive a car a certain way, you had better have a pretty good idea of how to drive yourself, not just a quaint theory about it. Having a grasp of historically accurate 18th century performance practice? That means having an understanding of the principals of bel canto, which aren't an affectation. The historical record is very clear. We know what the bel canto singer has to be able to do.
Either you can sing a real trill or you can't. Either you can sing messa di voce, or you can't. Either the tone is beautiful, the embodiment of chiaroscuro, or it isn't. Either you can sing a smooth crescendo and decrescendo without messing with the timbre of the tone, or you can't. Either you can speak, and then sing, the five vowels- /a/, /e/, /i/, /o/ and /u/ in a pure manner, or you can't (no American accent, thank you very much). How about let's start things off with one simple five tone scale? Better yet, how about a single tone, with no fancy funny business?
Real accomplishment leads to real knowledge. To the conductor learning his or her craft; if you won't learn to do these things, then at least have the grace and courage to listen to those who can.