The Choirmaster's Manual/Chapter 10
A WORD ON MEN'S VOICES
For the "mixed" voice, the following exercise will be useful for basses who have difficulty in getting a mixed voice—the voce mista of the Italians.
Sing the scale on "ah," changing to "aw" on or about B natural, and endeavor to "fill the mouth" with sound.Exercise 27.
Tenors use the same exercise, changing to "aw" on C♯ or D.
When these notes are obtained, practise the sliding vowels oo-oh-ah with the boys.
The following faults of tone are due to the causes named after them:
Too hollow sound:—Pharnyx too widely open.
Choked sound:—Throat muscles are rigid.
Guttural sound:—Tongue is curled up or stiffened.
Dental ring sound:—Mouth insufficiently opened.
Beware of too much nasal resonance. It is simply the effect of wrong direction in resonance, but is the cause of a great deal of unpleasantness, especially in men's voices, and is developed by many teachers through excessive practice on the syllable "ni."