Set to Sing

The mouth of the singer, who speaks correctly, is always set to sing. The muscles provide a mechanism by which the vibrating air receives the echo. The more the mechanism is exercised through the will, the more precisely it works, and greater the acoustic effect upon the resonating cavities. 
Cornelie van Zanten, student of Franscesco Lamperti in Bel-Canto des Wortes (1911)