ADDRESSING
VOCALREGISTER DISCREPANCIES:
AN ALTERNATIVE,
SCIENCE-BASED THEORY
OF REGISTER PHENOMENA
Leon
Thurman, Ed.D.
Graham
Welch, Ph.D.
Axel
Theimer, D.M.A.
Carol Klitzke, M.S., CCC/SLP
Second International Conference
The Physiology and Acoustics of Singing
6 – 9 October 2004
Abstract
This paper analyzes and evaluates several
explicit and implicit assumptions that are embedded in the concepts,
terminologies, and practices related to vocal registers. A reconciliation of the varied and
conflicting register concepts, terminologies, and practices is proposed,
including:
1.
a
brief historical context of vocal registers,
2.
a
documented science-based theory that accounts for vocal register phenomena from
perceptual, physiological, and acoustical perspectives,
3.
criteria
for selection of science-based categorical word labels for register phenomena
and suggested colloquial English terms that meet the criteria,
4.
how
the theory can be beneficially applied to the learning of efficient, skilled
singing and speaking when guided by music educators, choral conductors, singing
teachers, speech teachers, theatre directors, and when applied to therapeutic
clinical settings.
“You can't make me sing
that song. Those notes are past my break
and I'd have to use that weak part of my voice that just sounds awful. I won't do it.”
“I've always been a
soprano, so my lower pitch range is pretty weak. In fact, I was taught that singing in chest
register can damage your voice. I
certainly don't want to do that.”
“I've always been an alto
and when I sing pitches in the middle of the treble staff, my voice has a kind
of edgy, hard sound that sticks out in the choir. Then, above that, my voice is breathy and
weak. I've always wanted to be able to
sing with a high, clear soprano voice, but I can't.”
Male: “I can sing fine up
to about a D, and from G on up is sort of OK.
But right in between, my voice is real inconsistent. Sometimes it just gets weak, or it goes out of
tune, and sometimes it just flips or cracks.
Can you help me?”
“That Mariah Carey can
really sing high notes--and I mean high notes!
It's incredible. She was blessed
with a one-in-a-billion gift.”
Female: “I had one singing
teacher who called my head voice 'falsetto'.
Does that mean I'm supposed to sound like a man when he sings in his
falsetto?”
“What is my chest voice and
my head voice? And somebody told me
there is supposed to be a middle voice in between them. I'm confused.
Can you explain about my voices and show me when I'm supposed to be in
one or the other?”
“My choir director says
there are two voices--chest voice and head voice. My singing teacher talks about chest, middle,
and falsetto registers. I read a book on
voice that said there was a heavy mechanism and a light mechanism, whatever
those are. I wish you guys would make up
your minds; this is frustrating.”
Vocal registers
are controversial in the pedagogical, clinical, and scientific domains of
vocology. A well known general
definition of vocal registers is “...perceptually distinct regions of vocal quality that can be maintained over some ranges of
pitch and loudness.” (Titze, 2000, p. 282)
For centuries, however, concepts and practices related to vocal register
phenomena, including their linguistic labels, have been somewhat varied and
commonly contradictory.
Within both the
voice science and the voice education communities of the early 21st
century, considerable discrepancies remain in the conceptual frameworks,
terminologies, and practices that are related to vocal registers. To people who are not familiar with the
jargon of the voice-related professions, these discrepancies are puzzling,
confusing, and can even call into question the credibility of voice profession members.
In this paper, a
reconciliation of the varied and conflicting register concepts, terminologies,
and practices will be presented. It
will: (1) present a brief historical context of vocal registers,
(2) propose a
documented science-based theory that accounts for all vocal register phenomena
from perceptual, physiological, and acoustical perspectives, (3) propose
criteria for selection of categorical word labels for register phenomena and
suggest terms that meet them, and (4) suggest how the theory can be
beneficially applied to the learning of efficient, skilled singing and speaking
when guided by music educators, choral conductors, singing teachers, speech
teachers, theatre directors, and when applied to therapeutic clinical settings.
A BRIEF HISTORY OF VOCAL
REGISTERS
Perhaps for
millennia of time, singers and singing teachers have aurally identified changes
in voice quality when singing the consecutive fundamental frequencies (F0s) of a two-octave (or more) musical
scale. When transitions from one voice
quality to another occur, most singers report some sort of non-specific,
kinesthetically sensed, neuromuscular coordination adjustment in the
larynx. Among experienced or trained
singers, the transitions are perceived to be blended and smooth, but the
transitions are more commonly abrupt among inexperienced
singers.
The writings of
the Greek physician Galen (c. 129-200 AD) were the “bible” of medical anatomy
and practice for almost 1500 years after his death, but his observations
contained quite a number of inaccuracies.
Detailed knowledge of human anatomy and physiology began to be assembled
in the mid-16th century. A
prominent center for such study was the
Scientific
findings about vocal anatomy,
physiology, and the nature of vocal sound only began to be widely distributed
in about the middle of the 19th century.
With limited science-based knowledge of vocal anatomy, physiology, and
acoustics, singers and singing teachers had
to base their vocal concepts, terminologies, and practices substantially on
logical assumptions, personal perceptions, and metaphoric communications about
the nature of voices.
The term register was borrowed from the
terminology of keyboard organs (Merkel, 1863), and has been used in vocal
terminology since at least the 13th century (Duey, 1951). The earliest known writings about voice date
from that century. They were written in
Latin by two monks, Jerome of Moravia (c.1250) and John of Garland (c.1193 -
c.1270) (Large, 1973, p. 10; Mori, 1970; Timberlake, 1990). They wrote about the then current conceptual
categories and linguistic labels for the various “voices” in which singers can
sing.
When singers
sang in their upper pitch range, for instance, they presumably felt a
prominence of vibration sensations in the front, sides, and/or top of their
heads. We may presume that they
interpreted those sensations as meaning that their voices were “coming from”
their heads, so logically, they would call that way of singing head voice (Latin: vox captis = voice from the head).
When they perceived their head voice as producing subtle voice quality
differences, they are likely to have experienced differences in the vibration
sensations in their heads and believed they could “place” their head voices in
different areas of the head.
When they sang
in their lower pitch range, they are likely to have felt a prominence of
vibrations in their chest. We may
presume, therefore, that they interpreted those sensations as meaning that
their voices were “coming from” their chests and would call that way of singing
their chest voice (Latin: vox pectoris = voice from the breast or
chest). When they sang in their middle
pitch range, they no longer felt prominent vibration sensations in the head or
chest, but presumably felt a prominence of such sensations in their throats
because they called that way of singing their throat voice (Latin: vox
gutturis = voice in the throat).
When they changed from one voice to another, they physically felt the
transition from one “place” in the body to another, and they heard the sound quality of their voices change at the
same time. We may presume that this is
how a language of “voice placement” evolved.
In the 17th
century, Caccini wrote of voce piena
(full voice) and voce finta (feigned
voice). In 1627, Monteverdi wrote
of la
vocale della gola (the voice of the throat) and la vocale
In the 19th
century, Garcia and others wrote of three registers in ascending order of pitch
range: chest, falsetto, and head
(Garcia, 1855; also reported in Large, 1973, p.10; Timberlake, 1990). Merkel (1873), wrote of chest and falsetto
registers in men and low, middle, and high for women. In 1875,
John Curwen suggested thick, thin, and small as names for vocal registers (cited in Mackworth-Young,
1953). Browne and Behnke (1884) wrote
about five registers, i.e., lower thick,
upper thick, lower thin, upper thin,
and small. In the early 20th century,
Fröschels (1920) maintained that a “natural” voice had no registers, so that
voices were only one register. Wilcox
(1935) suggested the terms heavy
mechanism and light mechanism for
two vocal registers.
When singing in
their middle pitch range, some singers noticed sensations and sound qualities
that were different from those that they observed when singing in their
uppermost and lower pitch ranges. This
way of singing seemed to be a mixture of the sounds and sensations of chest and head or falsetto, so it
has come to be called a medium, or middle, or mixed register (Italian: voce
mista; French: voix mixte). When singing in middle or mixed voice,
singers observed transitions to other registers at both the top and bottom of
the mixed voice (Mori, 1970; Timberlake, 1990).
Its pitch range was said to be between the chest and the head or falsetto voices. According to Miller's description of the
Italian vocal pedagogy tradition (1977; 1986, pp. 115-149), the primo passaggio was the passage from
chest register to middle register and the secondo
passaggio was the passage from middle to head register. Men and women of various voice
classifications experienced the passages at slightly different pitch ranges.
Currently, the
terms head register and falsetto register are used by various
vocal pedagogues and voice scientists as labels for the different sound
qualities produced in middle and higher pitch ranges. For some singing teachers, however, head register is immediately above chest, and falsetto is above head. To
others, falsetto refers to all sound
qualities above chest in both males
and females, and sometimes the traditional high-range male falsetto is termed pure
falsetto. Among speakers of English,
the common, colloquial use of the
term falsetto refers only to the
female-like voice quality that males can make.
In some register
concepts, there are two “auxiliary registers”, one above and one below the more
commonly used head and chest registers.
Some prepubescent children, changing-voice males, and changed-voice male
and female adults can have a register that is variously labeled whistle, flute, or flageolet register that enables pitches that are
quite high (Cooksey, 2000, Large, 1973; Miller, 1986, pp. 147-148; Mori, 1970;
Timberlake, 1990). Some changed-voice
males and females are able to produce unusually low pitches below the more
commonly used registers. It has been
referred to as pulse or Strohbass register.
In the late
1960s, the research team of Minoru Hirano, William Vennard, and John Ohala (1969, 1970; Vennard, et al., 1970a,b)
heightened interest in the use of the scientific method to resolve many
controversies in the vocal pedagogy tradition, including landmark studies on
fundamental frequency, intensity, and register phenomena. They suggested Wilcox’s label heavy mechanism as a substitute for
chest register and his term light
mechanism as a substitute for registers above heavy
mechanism. In 1967, both Ralph Appelman
and William Vennard published landmark, science-based vocal pedagogy
books. In 1971, the late Wilbur James
Gould, M.D., founded the Voice Foundation in
In 1974, Harry
Hollien, an internationally prominent speech-voice scientist, presented four
new register terminologies for use in the speech science community, based on
his wide research experience:
1. Pulse register—a pulsated quality that
can be produced in a very low pitch range below modal, a sound quality that
also is called vocal fry.
2. Modal register—a heavier or thicker
voice quality that is produced in a lower pitch range. The label was a reference to the most common
"mode" of voice function, i.e., speech. It was the speech equivalent of chest
register in singing pedagogy.
3. Loft register—a voice quality that is
higher in pitch and lighter or thinner in quality, compared to modal register. It was the speech equivalent of head or
falsetto register in singing pedagogy.
4. Flute register—an even thinner quality
that can be produced in a very high pitch range above loft. In singing it is called falsetto in males and in females it is sometimes referred to as whistle register.
With increased
sophistication of instruments that are capable of documenting various vocal
phenomena came a curiosity about the actual anatomic, physiologic, and acoustic
realities of vocal registers and their transitions in both speaking and
singing. In the late 1970s, an
international medical organization, the Collegium Medicorum Theatri (CoMeT),
formed an international Committee on Vocal Registers with Dr. Hollien as
Chair. The committee included prominent
otolaryngologists, speech and voice scientists, and singing teachers. Their charge was to attempt a definition of
vocal registers perceptually, physiologically, and acoustically.
After their
early meetings, they agreed that at least four different vocal registers
existed, but that a definitive physiological and acoustic definition of all
register phenomena was not possible at that time (Hollien, 1985). The committee agreed that registers:
1.
involve a
series of consecutive fundamental frequencies that have the same perceived
timbre;
2. can be detected perceptually, and thus should be
recorded in the spectra of the different timbre groups;
3. are initiated by changes of laryngeal physiology
involving at least the internal muscles of the larynx.
The committee's
report questioned the scientific usefulness of the older names for registers
such as head and chest. The historic terms
attribute the identification of registers to areas of vibratory sensation in
singers. While vibratory sensations
definitely occur, they were not considered to be defining characteristics of registers. Defining characteristics are the physical and
acoustic events that give rise to the sensations.
While the
committee agreed that the sensations may be helpful in the education of singers
and speakers, they could not accept them as scientific evidence for defining
registers. The sensations themselves and their perceived
intensity vary widely between human beings, and replication of vibratory
sensations in groups of singers was nearly impossible to measure and study with
precision. Differences among perceived
vibratory sensations are the result of differences in: (1) anatomic structure and dimension among people,
(2) the nature of the physical coordinations used, (3) acoustic consequences in
body tissues, and (4) sensory perception abilities. The ability of the interoceptive and
proprioceptive sensory networks to bring vibratory sensations to conscious
awareness is variable. Interpretations
and verbal descriptions of their causes are subjective, and therefore, may be
inconsistent across human beings.
In order to
begin the process of register identification and definition, the committee
report identified four registers based on research at that time. In an attempt to reduce semantic confusion,
numbers were used to refer to the registers.
They were designated as #1, #2, #3 and #4 (Hollien, 1985). Based on information from the tradition of
singing pedagogy, a possible middle register between #2 and #3 was added and
designated #2A (e.g., Hollien & Schoenhard, 1983a,b). No scientific evidence for the existence of
this register was found by the committee at that time. The committee agreed that registers #2, #2A,
and #3 are the most frequently used in singing.
As voice science
and voice medicine became more prevalent, the National Institute on Deafness
and Other Communication Disorders (NIDCD), a component of the
As a result of
these developments, research into the phenomena of vocal registers has
increased over the past 25 years. In
addition to Harry Hollien, four voice scientists have consistently allied
themselves with various scientist and pedagogical colleagues to collaborate in
the study of vocal registers and associated voice qualities: Jo Estill, Donald Miller, Johann Sundberg,
and Ingo Titze (see references).
Within the vocal
pedagogy tradition—and among voice scientists—many questions have been raised
by: (1) the wide variety of register
concepts, terminologies, and practices, and (2) the variability of register
transition areas in the same voice
(Mörner, et al., 1964; Timberlake, 1990).
Eight explicit or implicit assumptions are imbedded in the current
jargon of vocal registers that are likely to be confusing to people who are
voice terminology novices:
1.
There
are speaking-voice
registers and singing-voice registers. An implicit assumption is that all human
beings have two voices, one for the “speaking voice”, and one for the “singing
voice”, and each “voice” has categorically different vocal registers.
2.
Chest
register is
associated with lower singing pitch range and a comparatively “thicker” voice
quality. An implicit assumption is that
it is activated by neuromuscular coordinations, or other phenomena, that occur
within the chest and thus produces perceivable vibration sensations therein.
3.
Head
register is
associated with higher singing pitch range and a comparatively “thinner” voice
quality. An implicit assumption is that
it is activated by neuromuscular coordinations, or other phenomena, that occur
within the head and thus produces perceivable vibration sensations therein.
4.
Falsetto
register is
associated with highest singing pitch range, or with all pitches produced above chest register, and a
comparatively “thinnest” (or “thinner”) voice quality. This concept has confusing implications. In Western cultures, it is strongly
associated with a female-like voice quality produced by males, but is a “false”
or “fake” voice that is of little or no practical use except in comedy. Vocal jargon novices may ask, “Do females
have a falsetto register?” and, “If ‘falsetto’ refers to the voice quality
that occurs in all pitches above chest register, how is it that at least two
categorically different voice qualities can be produced above chest
register? Does that not violate the
basic definition of a vocal register?”
5.
When
voices change from one register to another, unskilled vocalists typically
experience register breaks (abrupt transitions), but skilled vocalists
typically experience blended register transitions. Vocal jargon novices may ask, “What vocal
anatomy and physiology creates a ‘voice break’ in one person but not in another
person?”
6.
Middle
register is
associated with a middle singing pitch range and a voice quality that is a
“mixture” of chest and head (or falsetto)
registers. This concept also has
confusing implications. Vocal jargon
novices may ask, “How does one ‘mix’ two categorically different voice
qualities that, presumably, are produced by unique physiological
coordinations?” and, “If ‘falsetto’
refers to the voice quality that occurs in all pitches above chest register,
then how does this concept make sense?”
7.
A
lower and an upper passaggio pitch area are in all voices and they define the
lower and upper pitch range compass of middle register. Vocal jargon novices may ask, “How does this
concept make sense in the context of items 1 – 5 above?
8.
Each
register can be performed throughout the entire capable pitch range of all
singers, from lowest capable pitch to highest.
Vocal jargon novices may ask, “How does this concept make sense in the
context of all the above items?
What are vocal
registers, really? What anatomy and
physiology produce their acoustic phenomena?
How many registers are there?
What are the most accurate and helpful word labels for vocal registers? What happens physically and acoustically when
register events occur? Can the pitch
areas where register transitions occur be changed, or do they indicate
unchangeable, genetically inherited vocal characteristics? How is it that there can be so many different
register patterns in voices (e.g., strong lower-pitch-range registers and
weak/breathy upper-pitch-range registers, or vice versa, and register
transitions that occur around several different pitches)? How does “belting out a song” relate to
registers, and are there voice health issues involved in the use of belted
singing? How do registers and their
sound qualities relate to the musical styles of the world's cultures and
sub-cultures?
CONTEXT FOR A SCIENCE-BASED THEORY OF
VOCAL REGISTERS
An important
conceptual understanding that underlies this paper is that scientific
investigation is carried out by human beings and is, therefore, imperfect. Originally, the scientific method was
invented as a means of determining objective
reality and thus overcoming subjective
human bias, so that valid and reliable knowledge could be gathered. Totally “objective” scientific investigation
implies that the human beings who engage in scientific investigation are
entirely free from implicit assumptions and that they can disconnect the parts
of their brains that process feelings-emotions (biases) from those brain parts
that process perception and analytical conceptualization.
For instance, in
scientific investigations there is a possibility that human
investigators—inside or outside their conscious awareness—may orient research
procedures and findings so as to conform with previously held, emotionally
nuanced points of view. In addition,
technological instrumentation that is used to gather data for analysis may not
be sensitive enough to detect all of the phenomena that are relevant to a given
investigation, and sometimes, the instrumentation that could gather needed
information may not yet have been invented.
In spite of
these realities, the methods of science are still the best means we human
beings have yet devised to minimize
the influence of human bias. The “saving
grace” of scientific investigation is that, over time, human scientists will
question and reinvestigate previous findings and, based on a preponderance of
evidence, reconfigure theoretical explanations of “the nature of the world”.
The authors of
this paper do not claim status as “voice scientists”. We do claim to do the best we can to be
current with findings in the voice sciences, and to integrate that information
with our experience in helping people who are learning to sing and speak with
increasing skill and expressiveness. We
believe that such a background gives us credible grounds upon which to propose
a science-based theory of vocal register phenomena that we believe can resolve
historic conceptual, terminology, and practice discrepancies. In doing so, we hope to decrease doubts about
the credibility of the voice professions that occur among some of the people
who expect a high degree of consensus in voice-function knowledge among voice
scientists, speech pathologists, singing and speech teachers, choral
conductors, music educators, and theatre directors.
Some readers of
this paper are quite familiar with the scientific language of vocal anatomy,
physiology, and acoustics. Other readers
may be less familiar or unfamiliar with that language. This paper will attempt to present the theory
with both reader groups in mind. It also will assume that during the register
phenomena that we describe, (1) vocal anatomy and physiology are in a state of
health, and (2) the neuromuscular coordinations that enact basic breathflow,
phonation, and resonation are reasonably efficient. The authors acknowledge that some aspects of
this theory of vocal registers are not yet fully substantiated by scientific
research. If some of its provisions are
shown eventually to be inaccurate, that will be a learning moment, and that
learning will be celebrated because learning is what human beings do.
Two commonly
used linguistic nominalizations are: speaking voice and singing voice. The terms
denote concrete categorical differences between two “voices” in human beings,
but of course, human beings have one voice (one larynx and vocal tract), and
its neuromuscular coordinations produce all vocal phenomena, including speaking
and singing (details in Endnote 1). For
that reason, in this paper, there are no references to a so-called speaking voice and singing voice. Vocal
register phenomena, therefore, occur in all vocal sound-making, speaking, and
singing.
Using the
metaphor of a theatrical production, here is a review of the anatomy,
physiology, and acoustic processes that we regard as relevant to producing the
vocal phenomena that are referred to as vocal
registers.
The Producer is the genetic and epigenetic
expression that forms and maintains vocal anatomy and the neuropsychobiological
processes that activate and modulate vocal physiology.
The Playwright and the Technical and
Performance Director is the
central nervous system (CNS; brain and spinal cord). The CNS contains the vast neural networks,
and networks of networks ad infinitum,
that plan and enact the complex neuromuscular coordinations that produce all
overt and covert physical movements, including vocal phenomena such as vocal
registers. Learning new vocal abilities,
or altering already learned abilities, can only occur if relevant neural
networks are added to, or altered (for general reviews, see Fuster, 1997, 2003;
Holstege, et al., 1996; Huttenlocher, 1994; Thurman & Welch, 2000, Book I,
Chapters 3-9; Verdolini & Titze, in preparation).
The endocrine
and immune systems are Assistant
Directors that are interfaced with and modulate nearly all physical
functions, including those of the CNS.
Together, the Director and Assistant Directors coordinate all human
neuropsychobiological processing, including self-expression through symbolic
systems (languages, mathematics) and symbolic modes (music, dance, theatre,
painting, sculpture, architecture, and the like).
The Stage Crew is the peripheral nervous
system (PNS). It is made up of a somatic
division (cranial and spinal nerves) and an autonomic division (sympathetic,
parasympathetic, and enteric subdivisions).
The PNS has both sensory and motor nerves that are the interface between
the CNS and the external world, and between the CNS and internal bodily
processes. The motor functions of the
PNS are activated by integrative processing between sensory perception and
executive functions of the CNS.
The
playwright/director and crew have collaborated in a whole series of hit vocal
register dramatic and musical plays, such as:
A Streetcar Named Registers
A Funny Thing Happened on the Way to the
Registers
The Register Menagerie
Paint Your Registers
Joseph and the Amazing Technicolor
Registers
The Secret Register
How to Succeed in Registers without Really
Trying
Les Régisterable
The Leading Actors in these productions are
the primary laryngeal muscles that
induce the primary acoustic phenomena
of vocal registers. The role names of the leading actors refer
to the primary functions of the
“leading actor” muscles. (see Table 1)
1. Each of the
paired thyroarytenoid muscles (TA)
have two parts, a vocalis part
(thyrovocalis) and a muscularis part
(thyromuscularis). The thyrovocalis
parts extend for most of the length of the vocal folds and form their body or
core. The primary role of the TA muscles is to have a vocal fold shortening
influence within the synergistic functioning of all the internal larynx muscles
(especially in their interactions with the cricothyroid muscles). The
thyrovocalis parts appear to perform most of the shortening influence and both
parts appear to have a secondary adductory influence on the folds. For people who might feel averse toward the
use of anatomic terminology, or are too young or inexperienced to use it, the
vocal fold shortener muscles can be a
colloquial English term for the primary role of the thyroarytenoid muscles.
2. Each of the
paired cricothyroid muscles (CT)
have two parts, a more upright part (pars
recta) and a more oblique part (pars
obliqua). The most anterior ends of
the CT muscles are attached to the front of the cricoid cartilage and the
posterior ends are attached inside the lower lateral walls of the thyroid
cartilage. The primary role of the CT muscles is to have a vocal fold lengthening
influence within the synergistic functioning of all the internal larynx muscles
(especially in their interactions with the thyroarytenoid muscles). Their agonist-antagonist action with the
thyroarytenoid muscles creates a complex kind of “rocking” motion between the
cricoid and thyroid cartilages that alters the length of the folds. For people who might feel averse toward the
use of anatomic terminology, or are too young or inexperienced to use it, the
vocal fold lengthener muscles can be
a colloquial English term for the primary role of the cricothyroid muscles.
3. The spatial
location and configuration of the cover
tissues of the two vocal folds (official term: lamina propria) is altered by actions of all the internal larynx
muscles. The synergistic influence on
the folds’ cover tissues by the vocal fold shortener and lengthener muscles is
of greatest relevance to a science-based theory of vocal registers. The more the vocal folds are shortened, the
more thickened and lax the cover tissues become, and the more the vocal folds
are lengthened, the thinner and more taut the cover tissues become. These changes in the configuration of the
oscillating vocal folds influence the modes
of their oscillation and they change the characteristics of the voice source
spectrum.
The Major Supporting Actors are the
laryngeal muscles that induce a secondary
influence on the acoustic phenomena of vocal registers. The role
names of the major supporting actors refer to the secondary functions of these “supporting actor” muscles. (see Table
1)
1. The paired posterior cricoarytenoid muscles (PCA) are located at the rear area of
the larynx on the right and left sides.
They are attached to the cricoid and arytenoid cartilages in such a way
that they participate in abducting the arytenoid cartilages and thus opening
the vocal folds. Their primary role, therefore, is to have a
vocal fold opening influence within the synergistic functioning of all the
internal larynx muscles, especially in their interactions with the lateral
cricoarytenoid and the interarytenoid muscles.
Voice terminology novices may be more comfortable referring to these
muscles as the primary vocal fold opener
muscles.
2. The paired lateral cricoarytenoid muscles (LCA)
are located on the right and left sides of the larynx. They are attached to the cricoid and
arytenoid cartilages in such a way that they participate in adducting the vocal
processes of the arytenoid cartilages, and thus closing the vocal folds. Their primary
role, therefore, is to have a vocal fold closing influence within the
synergistic functioning of all the internal larynx muscles, especially in their
interactions with the posterior cricoarytenoid and the interarytenoid
muscles. Voice terminology novices may
be more comfortable referring to these muscles as one of the primary vocal fold
closer muscles.
Table
1
Summary of Internal Laryngeal Muscles
that Can Interact
to Produce Voice Source Spectra
Variations
that Can Be Perceived as Basic Voice
Quality Variations
|
Muscles |
Functions and
Influences on Voice Source Spectra |
|
Interarytenoids
(IA) |
·
A primary adductor of the cartilagenous portion of the
vocal folds |
|
Lateral
cricoarytenoids (LCA) |
·
A primary adductor of the membranous portion of the vocal
folds; ·
Agonist-antagonist interaction with IA and PCA to stabilize
vocal folds in many specific adductory positions |
|
Posterior
cricoarytenoids (PCA) |
·
Primary abductor of vocal folds; ·
Agonist-antagonist interaction with IA and LCA to
stabilize vocal folds in many specific adductory positions |
|
Thyroarytenoids
(TA) |
·
Primary shortener and thickener of the vocal folds ·
Secondary adductor of the vocal folds ·
Agonist-antagonist interaction with CT to stabilize the
length of the vocal folds in many non-specific and specific “settings” to
produce a wide range of F0s ·
Primary lengthener and shortener of the vocal folds when
not opposed by action of the CT |
|
Cricothyroids
(CT) |
·
Primary lengthener and thinner of the vocal folds ·
Agonist-antagonist interaction with TA to stabilize the
length of the vocal folds in many non-specific and specific “settings” to
produce a wide range of F0s ·
Primary lengthener and shortener of the vocal folds when
not opposed by action of the TA |
3. The singular interarytenoid muscle (IA) is located
at the posterior areas of the two arytenoid cartilages. It is attached to the arytenoid cartilages in
such a way that it participates in adducting the rear areas of the arytenoid
cartilages, and thus the cartilagenous portion of the vocal folds. Its primary
role, therefore, is to have a vocal fold closing influence within the
synergistic functioning of all the internal larynx muscles, especially in their
interactions with the posterior and the lateral cricoarytenoid muscles. Voice terminology novices may be more
comfortable referring to these muscles as one of the primary vocal fold closer muscles.
PLOT SETTING 1—Auditory Perception and
Memory of Acoustic Phenomena. When bodymind auditory systems perceive a
series of sound events that share the same (or nearly the same) acoustic
characteristics, then those characteristics are correlated within a number of
interconnected auditory neural networks to become a larger neural network that
extends into both the parietal and frontal brain areas (see Fuster, 2003). As a result, a distinct perceptual category
is instantiated within the neural networks—referred to as memory.
For instance,
when a range of different fundamental frequencies (F0s) are produced
but prominent spectral characteristics remain nearly the same, then a perceptual
category of perceived voice quality is formed even though the F0s
have changed. But when a range of F0s
occurs and a different set of
spectral characteristics are produced, then a slightly different combination of
neural networks process those events and another distinct perceptual category
is formed in memory. Language labels are
not needed in order for such percepts to occur, but typically, such labels are
assigned by human beings.
PLOT SETTING 2—Vocal Fold
Oscillation and Its Two Primary Modes. The most widely known
theory of how mucosal waves are initiated and sustained is called the myoelastic-aerodynamic theory of vocal
fold vibration (Van Den Berg, 1958). The theory proposes that vocal fold
vibration (complex mucosal waving) occurs when:
1. the vocal fold surfaces are sufficiently compliant and elastic;
2. the vocal
folds are adducted enough to create a sufficiently narrow glottis; and
3. the
pressure-induced airflow force is great enough.
During each oscillation cycle of the adducted vocal folds,
the folds are in alternate closed and open phases. During the closed phase of each vocal fold cycle, subglottal air pressure very
rapidly builds up enough to displace the surface layers of vocal fold tissue
and trigger an open phase. At one time, the Bernoulli effect was thought
to bring the vocal folds back together for the next closed phase, but in 1988,
scientific reservations were expressed (Titze, 1988; see also Titze, 2000, pp.
109-111). While the Bernoulli effect is
incidentally present, its influence has been considerably overstated in prior
versions of the myoelastic-aerodynamic theory of vocal fold vibration. The greater influence over the return of the
vocal folds from open phase to closed is:
1. the
constraining elastic properties of the folds themselves which reverse their
opening motion back toward closure, and
2. “...the
synchrony between the driving (subglottal) pressure and (alterations in) tissue
velocity...” during mucosal waving cycles (Titze, 2000, p. 110; parenthetical
expressions added for clarity).
Finally, there are two primary
modes of vocal fold vibration. One mode
can be described as a repeated medial-to-lateral-to-medial-to-lateral (and so
on) oscillatory motion. The other mode
can be described as a repeated bottom-to-top waving oscillitory motion that
mostly occurs in the more surface tissues of the vocal folds. In most speaking and singing, the two modes
occur simultaneously.
PLOT SETTING 3—Contributions to Basic
Voice Qualities by Internal Larynx Muscles and the Vocal Tract. The
vocal fold closer and opener muscle groups primarily
(not exclusively) contribute one range of basic voice qualities (see Figure 1),
and the vocal fold shortener and lengthener muscles contribute to another range
of basic voice qualities (registers, see later). When vocal folds are incompletely adducted to
some degree, they oscillate to create vocal sound waves, but pressurized air
molecules also are flowing through the opening between the folds, thus
producing air turbulence noise. A
combination of vocal tone and air turbulence noise produces a breathy family of voice qualities.
|
Figure 1 Vocal Fold Closer Muscles’ Contributions to Basic Voice Qualities |
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|
Breathflow “Energy” |
Muscle Energy |
||||
|
Whisper- |
Breathy |
Clear
& Richer Family |
Pressed-Edgy Family |
||
|
Noise |
Family |
|
Tense |
||
|
Family of |
|
P |
mf |
f |
Strained |
|
Sound |
|
firm |
richer |
richest |
Strident |
|
Qualities |
|
flutier |
mellow |
brassier |
Constricted |
|
|
|
|
warm |
|
Harsh |
When vocal folds
are adducted with a range of higher forces, and lung-air pressure is
correspondingly high, a pressed-edgy
family of voice qualities is produced.
Other terms used for this range of voice qualities are tense, tight, strained, strident, constricted, and harsh.
When vocal folds
are sufficiently adducted and “balanced” with appropriate lung-air pressure, a clear and richer family of voice qualities
can be produced. Because degrees of
adductory force are a major source of vocal fold amplitude/intensity during
speaking and singing, this family of voice qualities changes with perceived
vocal volume, but none of these voice qualities have breathy or pressed-edgy
characteristics. At softer volume
levels, a firm (not breathy) and flutier voice quality can be
perceived. At “middle-loud” volume
levels, a richer (more upper
partials) but mellow-warm voice
quality can be perceived. At “loud”
volume levels, a richest (even more
upper partials) and brassier voice
quality can be perceived.
When the vocal
tract changes its length and/or circumference dimensions, it has differential
effects on the pressures within the voice source sound spectra that are passing
through it (see Figure 2). Very
generally, when vocal tract dimensions are enlarged toward an extreme, lower
partials are amplified and upper partials tend to be damped, thus influencing
an over-full or over-dark family of voice qualities. Accordingly, when vocal tract dimensions are
diminished toward an extreme, higher partials are amplified and lower partials
are significantly damped, thus influencing an over-bright family of voice qualities. When vocal tract dimensions are optimally
configured, a relatively balanced complement of higher and lower partials pass
through and out of the vocal tract thus influencing a balanced resonance family of voice qualities that can range between
fuller and brighter.
|
Figure 2 Vocal Tract
Contributions to Basic Voice Qualities |
||
|
Overdark Family |
Balanced Resonance Family |
Overbright Family |