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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