Dear Vocalisters:
At the risk of sending a file that is too large I am enclosing material from Miller's "Structure of Singing, Velopharyngeal Closure" pages 63-68.
I quote: From ordinary X-ray sagittal projections, it is difficult to determine the extent of velopharyngeal (palatopharyngeal) closure in non-nasal sounds. Tomography provided pictures of sharper contrast and records a more accurate cross section. On the basis of tomographic studies, Bjork (1961, supplement 202, pp. 1-94) concludes that velopharyngeal closure may be less complete than X-ray photographs show. His study indicates marked narrowing of the nasopharyngeal opening both from lateral and from anterior-posterior aspects. Fant (1964, p. 231) suggests that the elevated velum as viewed tomographically may not occlude the velopharyngeal opening to the extent phoneticians often assume. Zwitman et al. (1973, p. 473) find that "[T]he degree of lateral pharyngeal wall movement varies among normal individuals. . . Conflicting descriptions of lateral wall movement probably are attributable to differences among individuals."
Zwitman et al (1974, pp. 3680370) established that several factors contribute to pharyngeal closure:
1 Lateral walls move medially and fuse, resulting in a purse-string closure as the velum touches the approximated section of the lateral walls. 2 Lateral walls almost approximate, with the velum contracting the lateral walls and partly occluding the space between them. A small medial opening is observed in some cases. 3 Lateral walls move medially, filling the lateral gutters and fusing with the raised velum as it contacts the posterior wall. 4 Lateral walls move slightly or not at all. Velum touches posterior wall at midline, and lateral openings are observed during phonation.
Nearly half of the 34 normal subjects examined in this study showed incomplete velar closure on non-nasals. Fritzell (1979, pp. 93-102) also suggests that muscular action in velopharyngeal closure varies among normal subjects. Such studies are of importance in providing probable factual support for theories of "the open nasal port" in some form in singing.
The possibility of at lease some coupling of the nasal resonator to the buccopharyngeal resonator has also been recognized by Sundberg (1977a, p. 90) in dealing with the acoustics of the singing voice: "It is just possible . . . that the nasal cavity has a role in singing of vowels that are not normally nasalized." It should be kept in mind that there may well be considerable individual physiological variation with regard to nasopharyngeal coupling.
Implications for the technique of singing are significant. Limited degrees of nasopharyngeal coupling (some aperture of the port) seem to be induced by the numerous vocalizes that make use of nasal consonants as "placement" devices. The perception of nasality in non-nasals is always, of course, to be avoided. However, vocal sound perceived by the listener as resonant but non-nasal may in fact result from some degree of nasopharyngeal coupling (house and Stevens, 1956, p. 218). The ratio in balance between oral and nasal resonance may depend on how the posterior apertures into the nasal cavities relate to the size of the oral cavity. Nimii et al. (1982, p. 250) comment that
"[I]t is apparently quite usual for velar elevation to vary during connected speech, with changes in velar position, and thus in velopharyngeal port size, produced to enhance or prevent nasal coupling, as needed, for the segments in the phonetic string. . .[V]elar elevation varies directly with the oral cavity constriction of oral segments"
This group of researchers concludes that one must expect "some individual differences, even among normal speakers" as to the mechanical means for velopharyngeal closure (1982, p. 255).
The answers are not all in, regarding the mode by which velopharyngeal closure may be modified. According to Nimii et al. (1982, p. 253):
"There is general agreement that the velum is elevated and retracted primarily by the levator palatini muscle . . The point of controversy revolves around the putative role of other muscles in the velopharyngeal port region in bringing about movement of the lateral pharyngeal wall at various levels relative to the point of velopharyngeal closure."
This piece of research concludes:
"We believe that the levator palatini is the muscle primarily responsible for the medial movement of the lateral pharyngeal wall from the level of velopharyngeal closure (which varies with the type of phonetic segment produced) to the superior limit of that movement. That the interpretation that the levator palatini is responsible for both the lateral wall and velar movements is a valid one is supported by the data . . .
How one conceives of "opening the throat" and "placing the voice" leads directly to specific kinds of muscle activity in the velopharyngeal area. The levator veli palatini (levator palatini), the tensor veli palatine, the palatoglossus and palatopharyngeus, and the musculus uvulae (see Appendix III and Figures 4.7, 4.8, and 4.9) respond to such concepts. The presence or lack of "resonance" in the singing voice is closely tied to adjustments made in the velopharyngeal region. The extent to which the nasal cavities are united with the rest of the resonator tube partly determines the perception of "resonance". As with the exact character of velopharyngeal closure itself, not all the answers are clear regarding the degree to which velopharyngeal closure may be modified in singing. Additional attention to balanced resonator adjustment through the use of consonants (including the nasal) will comprise the material of other chapters. However, the resonant, well-balanced vowel in singing must first be considered.
Chapter 5: The Well-balanced Vowel follows. -- Lloyd W. Hanson, DMA Professor of Voice, Pedagogy School of Performing Arts Northern Arizona University Flagstaff, AZ 86011
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