There seems a divergence of opinion as to what vowels are most
beneficial in technical practice and study. Galli-Curci says: "In my own
study I use them all, though some are more valuable than others. The Ah
is the most difficult of all. The O is good; E needs great care. I have
found the best way is to use mixed vowels, one melting into the other.
The tone can be started with each vowel in turn, then mingled with the
rest of the vowels." Mme. d'Alvarez often starts the tone with Ah, which
melts into O and later changes to U, as the tone dies away. Bispham has
the student use various vowel syllables, as: Lah, Mah, May, and Mi. With
Oscar Saenger the pupil in early stages at least, uses Ah for vocalizes.
Duval requires students to use the vowel Ah, for exercises and scales,
finding the others are not needed, especially excluding E and U as
injurious. Griffith uses each vowel in turn, preceded by all the
consonants of the alphabet, one after another.