|Jan van Eyck, detail from Ghent Altarpiece, 1432|
"A singer should not sing through his nose. He must not stammer, lest he be incomprehensible. He must not push with his tongue or lisp, else one will hardly understand half of what he says. He also should not close his teeth together, nor open his mouth too wide, nor stretch his tongue out over his lips, nor thrust his lips upward, nor distort his mouth, nor disfigure his cheeks and nose like the long-tailed monkey, nor crumple his eyebrows together, nor wrinkle his forehead, nor roll his head or the eyes therein round and round, nor wink with the same, nor tremble with his lips, etc."
Christoph Bernhard, Von der Singkunst oder Manier (1650)Don't let your singing career be ruined by the age-old problem of Bitchy Singing Face.