modification.There is no disputing

modification.
There is no disputing the fact that modification of vowels inspires much controversy. However, the conviction that modification of vowels is unnecessary does betray a certain ignorance. It is true that singers can sing any note on any vowel, limited only by the physical boundaries of their range, but some vowel forms will have constructive interaction with the vocal cords (aid and amplify their air pressures), and other vowel forms will have a diminishing acoustical interaction (distort and diminish the cords’ air pressures). A bad tone fights with itself; that is, two vibrators interact badly with each other. For example, in stringed instruments the conflict is between a string and the resonator; in the organ the conflict is between the reed and pipe. In the voice, the conflict is between the vocal cords and the vocal tract. 1
Needed is an extended method of bringing sung pitch and the resonance of vowels into their best relationship, or, bringing the frequencies of the vocal cords and the vocal tract into concord with the various pitches and vowels. Voice pedagogue Berton Coffin, together with acoustician Pierre Delattre, worked out the practical details of a system that allowed singers to choose the vowel that would give a compatible frequency with the pitch. This system of vowel modification is found on the Vowel Chart that is included with their book, Overtones of Bel Canto.
Those opposed or indifferent to modification include many choral directors and some voice teachers. Pressed for the reasons behind their objections, voice teachers generally cite the seeming mechanistic quality of the method; choral directors cite lack of blend and unclear diction.. Often, in an effort to promote the elusive “blend,” choral directors subscribe to reducing the sound of their singers to the resonance level of the least resonant voice in the group. To encourage clarity of diction they often embrace a theory of using only “pure” vowels, by which they may mean speech vowels.
By avoiding vowel modification as a part of their technical training, voice teachers have ignored a means of producing in their singers a more resonant, carrying tone and a more efficient way of achieving it, not to mention more control over dynamics, and more ease in upper range singing. As for choral singing, holding all choral voices back to the piano level of the least vibrant voice in the group not only produces a less beautiful tone but is actively unfair to and dangerous for the larger, more resonant voices in the group. Dale Moore, noted pedagogue, has this to say: “I would rather have a soprano of potentially operatic caliber serving as part of a cheerleading squad than have her singing in a group where the tonal ideal for a soprano is the sound of a tired English choirboy.”2 Paul Kiesgen, celebrated teacher of voice and vocal pedagogy, echoes Moore: “Loud singing with inadequate vocal technique can be harmful....Poorly produced soft singing, however, can be equally harmful....For most voice students, soft singing is the last skill mastered and one of the most difficult to acquire.”3 The result of improperly produced soft singing is often perilously close to “pushing,” a term usually applied to loud singing.
The following true story illustrates the power of using the constructive interaction of modifications that “beef up” the singers’ formant, which was done here by means of mechanical