25. The Linguistics of Music
Thus, at the foundation of a person’s musical development is the singing of music out loud with the voice. Everyone understands this, even devotees of the Alphabet System. Often, when using the Alphabet System, the teacher attempts to sing the melody by letters with the student.
However, the names of the letters are far from being as comfortable for singing as Solfeggio. Both English pronunciations [see, dee, ee, ef, jee, ey, bee] and Latin transcription [tse, deh, eh, ef, jeh, ash, ah, beh] aren’t suitable for the development of the throat. Let’s analyze this in detail.
Linguists consider the vowels “A,” “O,” “E,” and “I” as fundamental, focal for the speech apparatus in all languages. The vocal sound “Eh” has been classified as secondary. The singing of the sound “Eh” requires a tension on the vocal chords and a half-opened jaw. That aside, the sounds of “Ey” and “Ef” are locked by consonance and aren’t open enough to be connected to other vowels.
The remaining sounds of the Alphabet System depend on the vowel “I” [ee]. Even though it is classified as a fundamental tone of speech, is still tenses the throat, requires the jaw to be open just 15%, and causes five of the seven notes to be voiced in a rather sharp timbre.
The syllables of the Solfeggio System are incomparably more comfortable for the apparatus of the voice. They are composed of a variety of the fundamental tones: “Oh” (50% opening of the jaw), “Eh” (50%), “Ah” (100%) and “Ee.” The more varied the vowel sounds, the more varied the movements of the facial and jaw muscles. Sounds are perceived on a diversified muscle level, and this helps to better memorize the music text. The alteration of vowels gives the vocal chords a stable phonetic foundation and trains the separate muscles of the throat. This provides each note with a physiological uniqueness that helps to more precisely memorize the pitch of the sound.
 Wikipedia’s entry on “Tenseness” offers some additional information as well as a bibliography of related works on phonetics.