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Voice analysis in ethnomusicology:
De-mystifying Bulgarian singing

Research results: The de-mystification process

Few people ever pause to consider the miracle of speech and song. If one takes the time to do so, the miracle-actually a constellation of miracles-is revealed in all its elegant complexity. The experience can be both humbling and exhilarating. 1

The process of voice production

To begin with, some basics of voice production should be explained to demonstrate that the voice is not actually such a mysterious instrument and so the terminology used to describe voice production can be understood when applied to Bulgarian singing. Fundamental to the creation of sound is breath flow. The human breath apparatus is made up of the thoracic cage which houses the lungs and is composed of the sternum, ribs and vertebrae; the internal and external intercostal muscles, which aid in the elevation and depression of the ribs; and the diaphragm, a dome-shaped muscle that divides the thoracic cavity from the abdominal cavity which is relaxed during the course of the whole phonatory process except during inspiration between phrases. Conscious control over the diaphragm is not possible, although many singing teachers will incorrectly refer to the diaphragm as being able to control and support the sound.2 Figure 1 shows the parts of the body involved in the human breath apparatus,3 and the movement of the breath apparatus before singing is well described below:

On inspiration, the diaphragm presses on the abdominal viscera through a downward and forward movement. The abdomen, in response to that action, swells outward.... "The central tendon, applied to the abdominal viscera ... becomes a fixed point for the action of the diaphragm, the effect of which is to elevate the lower ribs and through them to push forward the body of the sternum and the upper ribs" ... The cone-shaped curve moves downwards ... causing the lungs to expand ... during subsequent relaxation, "The diaphragm reverts to its dome-shaped form, pushed upwards by the contents of the abdominal cavity. The lungs are also pushed upward, expelling the air content as they are compressed." This mechanical action involves simultaneous movement in both abdomen and chest, serving to alter chest cavity volume and subsequently, the volume of the lungs, all being the inevitable result of chest wall activity.4

Figure 1. The breath apparatus
Figure 1. The breath apparatus

Human sound is created by the production of airflow by the breath apparatus through the sound generator-the larynx-that is made up of cartilage, ligaments and muscle (see figure 2).5

Figure 2. The larynx
Figure 2. The larynx

The vocal folds are two bands of muscles situated in the centre of the larynx that are pivoted together by the thyroid and arytenoid cartilages when hit with airflow to assist in the creation of sound (see figure 3.)6

Figure 3. Vocal folds and surrounding parts in the larynx
Figure 3. Vocal folds and surrounding parts in the larynx

The primary function of the vocal folds is to keep foreign objects out of the trachea, which is the passageway to the lungs, but the other more advanced purpose of vocal folds is to create sound, whether that is manifested in speech or song. Puffs of air pressure are built up behind the vocal folds and expelled through them causing vibration of the folds. The number of times per second that the puffs of air occur determine the sound frequency. The vocal folds stretch vertically and become thinner when creating high pitches and they shorten and thicken to create low pitches. The sound created resonates in all of the enclosed air spaces from the top of the vocal folds to the pharyngeal cavity and the oral and/or nasal cavities and is expelled through the mouth and/or nostrils. The parts of the mouth that play important roles in the articulation of words in the vocal production process include the tongue, the soft and hard palates and the lips.7 Figure 4 shows the relevant parts of the vocal instrument.8

Figure 4. Sagittal view of the vocal system with the resonance spaces shaded
Figure 4. Sagittal view of the vocal system with the resonance spaces shaded

The positioning of the larynx and the different ways in which one can manipulate the various parts of the mouth and throat create different timbres. One of the major techniques involved in creating the Bulgarian sound is the high positioning of the larynx in the upper register of the voice. The larynx may be consciously raised to produce a bright vocal timbre by shortening the supraglottic vocal tract,9 and it can be lowered to achieve a deeper timbre.10 This is a vastly different concept to the theory in the classical school of singing where it is generally believed that the conscious depression or elevation of the larynx should be avoided and the larynx should be poised and stable, neither rising nor falling with vowel change or inhalation.11


This chapter aims to show that the Bulgarian vocal style is a type of "belting". Belting is a vocal quality heard in many sung musical genres around the world including Broadway singing, pop singing, jazz singing, country singing and folk singing. It is an under-researched area, even though there have been numerous articles on the subject over the last two decades, because, similarly to the Bulgarian voice, the actual vocal quality of belting has not been the object of serious voice research.12 This means that the term "belting" is often used incorrectly, and incorporated into vocal technique incorrectly, resulting in damage to the throat.

Belting is controversial because amateurs who try to copy their idols in belting out a song without seeking proper training from a voice teacher will often damage their voice, and produce a harsh, raspy sound that doesn't have the fullness of the harmonic spectrum that comes with open throated belting.13

Because of the negative connotations of the term "belting", it is often rejected by singers and used instead to describe a bad sound or incorrect sound, instead of an actual vocal style that you can develop safely with practice. Jo Estill and Robert Edwin are both at the forefront of research into belting and have found some very interesting results. Estill describes the belting voice:

It is loud, brassy, sometimes nasal, always "twangy", and yes, it sounds like "yelling", and certainly would be, if the yelling had not been shaped by the organization of frequencies (notes) and time (rhythm) into meaningful music.14

Richard Miller, primarily a specialist in the theory and practice of the classical bel canto vocal style, hasn't studied belting specifically, but has researched in depth vocal fold function and the physiological workings of the voice. In an article by Edwin entitled "Belting 101", he mentions that many vocal teachers describe belting as "chest voice singing", which is in fact incorrect. He refers to Miller's theory of alternate terms for "chest" and "head" voices as detailed in his book The Structure of Singing:

It is pedagogically convenient to call a vocal register in which the thyroarytenoids are predominant, the heavy mechanism , and to call those registers in which the cricothyroids are predominant, the light mechanism , so long as it is understood that there are not actually two separate mechanisms, but changing, dynamic balances among the laryngeal muscles.15

Figure 5. The intrinsic muscles of the larynx
Figure 5. The intrinsic muscles of the larynx 16

Edwin describes the thyroarytenoid muscles as the "closers" of the vocal folds and the cricothyroid muscles as the "stretchers" of the vocal folds. Edwin emphasises that it is a misconception that belting uses only the thyroarytenoid muscles. What actually occurs in belting, from about F4 and upwards in women, is a co-ordinated effort between both the thyroarytenoid and the cricothyroid vocal fold muscles, which is in fact a technique evident in classical singing also, but usually termed "chest mix" or "voce mista" instead.17 The difference between classical singing and belting is that belting takes this co-ordinated muscle movement to a higher range of the voice than classical does. In the higher range of classical singing, it is generally only the cricothyroid muscles that are in action. Edwin has found that the belter's technique incorporates a higher laryngeal position, a tightened, narrower pharynx, a lateral mouth, and a longer closed-phase of the vocal fold vibratory cycle than in classical singing.18 This causes little or no vibrato, a phenomenon evident in Bulgarian singing. Miller defines the term "vibrato" as:

A phenomenon of the schooled singing voice; a pitch variant produced as a result of neurological impulses that occur when proper co-ordination exists between the breath mechanism and the phonatory mechanism; a natural result of the dynamic balance of airflow and vocal-fold approximation.19

Estill's "Belting and Classic Voice Quality: Some physiological differences" discusses some experiments she and her associates undertook on the muscles of the vocal folds of a student. Her subject sang various phrases in an operatic voice, a belting voice, and in spoken voice. She found that there was a higher level of activity both in the vocalis or thyroarytenoid muscle and the seven extrinsic muscles in belting than in either speech or opera. She draws attention to the laryngeal position in belting, which is higher and tilted differently to the operatic laryngeal position.

From the data, the major difference between the two qualities appears to derive from laryngeal posture-the relationship of the thyroid to the cricoid cartilage. Whether the cricoid is fixed and the thyroid tilts anteriorally (as in opera) or the other way around (as in belting) may depend on ... whether you are "used" to using the voice one way or another.20

Estill also mentions that overall, belting involves harder work from the muscles than in operatic singing, with the exception of the tongue, which helps to widen the pharyngeal space in operatic singing. In belting, one attempts to reduce the size of the pharynx to create a bright, brilliant sound, so the tongue is not involved in this process.21

This study is proposing that there are different types of belting, and Bulgarian singing is one of these types. While this research is limited in producing scientific evidence for this premise, due to time, space, lack of equipment, funding and ethical considerations concerning the study of the human voice, there is evidence given by the interviewees and the research into Bulgarian singing presented in chapter two to suggest that belting and Bulgarian singing are very similar. This concept will be discussed following the presentation and discussion of interview results.

Table 1. Summary of Interview Results Part 1

Q. No. Summary of Question Angela Lily
1 Bulgarian Ancestry? No No
2 Qualifications? Ethnomusicologist, professional singer and ex-director of the UCLA Bulgarian women's choir SuperDevoiche. Professional singer in US-based Bulgarian choirs Kitka and Svitanje
3 Areas of resonance? Throat, base of tongue, chest. Chest, belly, back of throat, away from the nose.
4 "Open-throated"? No, actually "tensed-throat", tight vocal chords. This is an accurate and useful term. You should move the muscles of the throat and back of the mouth out of the way to allow space for overtones to develop at the back of the throat so the sound can come cleanly straight out of the mouth.
5 "Belting"? Applies to more rural vocal style, not so much to professional singers and choirs. I've heard of this term in relation to Broadway singing. It's possible there is some similarity [between Broadway and Bulgarian]. My intuition is that belting is not as relaxed and controlled.
6 Tongue position? Raised base of tongue, tongue does vibrato and most ornamentation. Relaxed tongue, shouldn't be forced back or down, back of throat should move away from tongue, but tongue keeps natural high position.
7 Laryngeal position? Raised Relaxed, but not sure.
8 Pharyngeal position? ? Throat should be as large and open as possible, back of throat lifted to create round open space.
9 Soft and hard palates? Minimise contact between tongue and soft and hard palates to maximise volume. Hard palate helps resonance and in the production of many consonants. Combination of soft palate, uvula and back of the throat is responsible for ornamentation including the thressane, the mordants and the controlled vibrato.
10 Vowel positions? Italian vowels [i, e, a, o, u] plus uh]. Tongue isn't as close to roof of mouth with [i] as in speaking, [u] usually becomes more like [o] for more sound, and [a] is often quite dark. [i, e, a, o, u, oo, uh]. Stressed [e and o] are open - like [eh and aw], unstressed [e and o] are closer to [i and u]. [i and u] are as closed as an open throat will allow, if unstressed they are more open. Stressed [a] is like bright Italian [a] but unstressed is like [uh].
11 Jaw position? Moderately wide open, not as wide as opera singers, jaw shouldn't move during ornamentation. Relaxed, pushed a hair forward.
12 Nasality? No nasality. Raised larynx causes resonance in nasal-chamber, but if nose is plugged during singing, it is evident that the sound is not nasal because sound still comes out. Some regions use nasality (e.g. Pirin mountains) but generally the style is not nasal. Bright overtones due to raised back of throat are often mistaken for nasality. Check for nasality by pinching nose to see if the sound changes at all. If it does, lower the resonance from the nose to highest part of the back of the throat.
13 "Chest" and "head" voice? There is gurlen glas - throat voice and. faltset - falsetto. Throat is generally used in non-professional contexts, except in some areas where a distinct faltset is used, in choirs chest voice is used primarily, but mixed voice (strident falsetto) is used for higher notes Bulgarian singing mainly uses chest voice or low register, except for "glottals" (mini yodels) and "ikhs" (high pitched dissonant notes at ends of phrases). Sopranos often use a "mixed tone" - a blended quality to get the height of the head-middle voice with the focused edge of the chest register. I don't like the terms "chest" and "head" though. A singer in the Bulgarian choir Elenka told us to sing like opera singers, not like pop singers, as the sound should come from the guts, not the throat, whether using head or chest voice.
14 Breath management? Not much air needed to produce sound, not full torso breathing like opera If you maintain proper diaphragm support and have an open, unrestricted throat, breath isn't much of a problem.
15 Bulgarian terms for technique and timbre? Every singer uses her own terms, some terms include "metallic" for strident voice, mazhen for buttery voice and piskliv for reedy voice Named after regions: Pirin, Macedonian, Rhodope, Shope and Thracian. They each have characteristic timbres. There is also the modern Wedding style versus the straight-tone classical style, urban versus village styles, Communist approved and unapproved styles and also the ethnic minorities - Jews, Roma and Vlachs.
16 Vocal range? A3 - F5 but C3 - D5 is most comfortable Low-voiced women can hit C3 or D3, most women can reach F3. Women's chest voices can reach F4, high-chest can reach C4 and D4, and with a mixed-tone, higher notes are possible.
17 Origins of Bulgarian vocal style? Too much to list here Influences from Middle East, Ottoman Empire, Arabic-like ornamentation, affinities to Russian/Ukranian styles (use of drones, yodels, high pitched screams), Central Asian music (pentatonic scales, glissandos, drawn out melodies), Mongolian.
18 Relationship of Bulgarian language to vocal style? Vocal production in Bulgarian speech is akin to the singing style, no diphthongs. Mostly I hear this in the bright, high, focused quality of both the singing the way the language is spoken.

Table 2. Summary of Interview Results Part 2

Q. No. Summary of Question Moya Tatiana Tzvetanka
1 Bulgarian Ancestry? No Yes Yes
2 Qualifications? Professional singer and Director of Canberra-based choir Can Belto Professional singer and teacher of Bulgarian singing in Bulgaria & Boston Professional singer, teacher and conductor of Bulgarian folk music, based at UCLA
3 Areas of resonance? Chest, sinus. Chest, sinus, head. Chest area.
4 "Open-throated"? I use the term "open-throated" when I run voice workshops, but to actually create a Bulgarian sound, to get the harsh sound, it is actually a relaxed but restricted throat. It became known as "open-throated" singing for a long time there, but in fact in the last few years I've thought about that and thought that's not true of Bulgarian. Blank Open throat singing is a better term for opera singing. In Bulgarian folk singing, we don't use a particular term. I could say that the sound is open and outside, but this doesn't mean that the throat needs to be open. In order for one to have a sharp and clear sound, one has to have very organized and focused use of the vocal chords.
5 "Belting"? I think it has very similar qualities, but there is a difference in producing an "all-purpose belting voice" and a specific "Bulgarian voice". Bulgarian voice is belting, but little shifts are made to get a particular sound. "Belting" resonates lower (has a deeper tone quality) than "Bulgarian". Don't know this term. No such term in Bulgarian folk singing.
6 Tongue position? Back, not on roof of mouth, tip behind front teeth, articulates words, more movement for Bulgarian "l" than English "l". Back, down, loose. The tongue is usually resting.
7 Laryngeal position? High. Relaxed, low. The larynx and the vocal chords are the most important parts in the singing as general. The larynx is in low position when we sing low, and is high when we sing high.
8 Pharyngeal position? Widened and tightened, kept rigid. Blank The pharynx is tense no matter how low or high we sing.
9 Soft and hard palates? Raised soft palate, not sure about hard palate. Not hitting soft palate with air as in head voice. Soft and hard palates play a role in building in building the timbre sound of singer. In contrast, they do not play role in building the sound. They are just like a massage of the voice.
10 Vowel positions? Forward, [a, e, i, o, u] As in normal speaking voice. [a, e, i, o, u]
11 Jaw position? You don't open your mouth very much- your jaw doesn't move much at all so as to create a small focused sound. Loose, relaxed. Relaxed, as when you talk.
12 Nasality? It sounds nasal but it's not. There is a similar tone quality, but if you pinch your nose while you're singing you will notice that the tone quality doesn't change which means it's not nasal. We don't use the nose, the singing is not nasal - ignore the nose, use the sinus. It definitely has to be avoided.
13 "Chest" and "head" voice? "Basic" voice or "chest" voice (same thing) used primarily, and head only sometimes. For Balkan singing we use "chest voice" for low singing and "high voice" for high singing. I use the term "head voice" for "bel canto" singing. There is no head voice in Bulgarian folk singing. It is not employed at all. The voice is coming only from the chest.
14 Breath management? Breathe without lifting your shoulders, use of intercostals & abdomen, expanded torso like bellows, the focused sound doesn't let breath escape so long phrases are easier. Diaphragm is used to hold and control the air. The breathing is released with the diaphragm.
15 Bulgarian terms for technique and timbre? Technical terms: shakes (like vibrato), bleats, yodel flips, slides, twiddles, yips. Blank There are many timbres in the Bulgarian folk singing: sharp, soft, velvet, metal, deep, and so on. They can be reached with a lot of practice of the voice muscle, and this leads every singer towards building her own timbre
16 Vocal range? C3-F5, but it varies greatly from person to person. Range gets lower with age. 2 octaves A3-G5, however, not all singers can reach these borders.
17 Origins of Bulgarian vocal style? Bulgarian singing was partly developed because they sang outside and they had to develop a style that carried, and it was very much part of the lifestyle. You sang while you worked, you sang to keep the time passing, you sang because you had a rhythm and it helped your rhythm and breathing, and you sang because then you felt like a community- very much call and response. Blank The history of the country has a lot to do with the origin of the Bulgarian singing style. Bulgarian singing is kind of a soul singing, and everybody knows how sad the Bulgarian soul was. This type of singing is going through the singers' soul, and this is the reason for such amazing singing. No wonder why the most beautiful Bulgarian songs are the slow songs with sad lyrics.
18 Relationship of Bulgarian language to vocal style? The Bulgarian speaking voice is placed differently to ours-more forward. If the speaking voice of any culture is placed in a way then probably a lot of their traditional music is placed in the same part. The language is melodic, very expressive for music. Vowels are rich and good for singing. The Bulgarian language is a bright language with open, clear vowels, and it is a prerequisite for a bright and open singing where the sound is not in the head but outside.

Discussion of interview results

The interview results can be summarised in the following way:

  • Sound resonance occurs in the throat, chest, belly, sinus cavities, but rarely in the nose.
  • The singing style is not really considered to be "open-throat" singing because although the throat should be relaxed, the vocal folds are tense and the laryngeal position is generally high except on low notes, and the pharynx is tense. Just because the sound developed in the "open" doesn't mean the sound itself is "open", in fact the opposite is necessary for the sound to carry.
  • The soft palate is raised and should not have cold air hitting it, the hard palate helps resonance and consonant articulation and both palates help to create different timbres and should move away from tongue to maximize volume.
  • The jaw is loose and relaxed, generally unmoving, perhaps slightly protruding, and the mouth doesn't open very wide.
  • The tongue is relaxed, high at the back, assists in ornamentation in some cases, articulates words, and the back of the throat should move away from the tongue.
  • The term "belting" is not used in Bulgarian singing, but it is possible that this sound is similar to the Bulgarian sound, particularly in rural singing as opposed to professional choir singing, but there would be slight differences. (It is interesting that all but one of the interviewees either hadn't heard of the term "belting" at all, or rejected it as a term to describe Bulgarian singing).
  • The main voice used is "chest" voice or "low" voice, but there is evidence of a "mixed" voice in some singers on higher notes. "Head" voice is called "high voice" and is rarely used, except in high ornamentation.
  • The singing vowels are as in the Italian [i, e, a, o, u] with the addition of [uh] and all except [uh] are generally forward like the Bulgarian language. (There are no diphthongs).
  • The lowest and highest notes that some women can reach are C3 and G5, but the general range is more like F3-D5.
  • The breath is supported with the diaphragm, but is not generally thought about specifically, as the tight vocal folds don't allow breath to escape, so long phrases are easily sung.

Although there are definite similarities between the interviewee's answers, including where the sound resonates, breath management, the use of chest voice, tongue position, vocal range, lack of nasality, timbre, vowels, the origins of the Bulgarian vocal style and the relationship of the Bulgarian language to vocal style, there are obvious differences of opinion on particular topics. For instance, "open-throated" is a term described differently by everyone and obviously causes some confusion. This question obviously relates to the question regarding pharyngeal (throat) position. Tatiana left both questions blank, so a discussion of her comments cannot be undertaken here. Angela understood the term "open-throated" as relating to the vocal cords, and therefore rejected the term, as she said that the vocal cords are tense, not open, and she wasn't sure how to describe the pharyngeal position. Moya and Tzvetanka both rejected the term "open-throated", saying that the throat actually has to be rigid, and they both then also referred to sensations of tenseness in the question of pharyngeal position. Lily is the only one with the opinion that the term "open-throated" is a good term to describe Bulgarian singing, and therefore she also mentions that the pharynx should be as wide as possible.

If it is hypothesised that Bulgarian singing involves belting, then Bulgarian singing actually involves a tightened, narrow pharyngeal position, a high laryngeal position and tight vocal folds. Therefore, the term "open-throated" in conjunction with Bulgarian singing is generally used inaccurately amongst singers, but it is obviously used in an attempt to convey a vocal quality that is difficult to verbalise, and is perhaps learnt best by imitation. It is perhaps more accurate to describe classical singing as "open-throated", as Tzvetanka mentions (and Estill concludes in her research), because of the incorporation of a low larynx, widened pharynx, and shorter closed phases of the vibratory cycle of the vocal folds therefore causing a sense of openness due to vibrato.

The question of whether nasality is incorporated in Bulgarian singing is very interesting. All the interviewees were very strong in their answers to this question, stating that Bulgarian singing is not nasal. Why is it then, that many descriptions of the Bulgarian sound are described as being nasal? Miller's research shows that perceived nasality in the voice is actually due to frontal vibratory sensations from the resonator system formed by the mouth and the pharynx, called the buccopharyngeal resonator. Miller states that this vibration is often associated with concepts of "forward placement" and "brilliance", resulting in the perception of a nasal quality in the voice, especially when nasal phonemes are articulated, but also during the articulation of non-nasal phonemes. Nasality will be evident in vocal timbre if the velopharyngeal port (the passage from the back of the nostrils to the soft palate) is open, but if it is closed, and the sound is still perceived as "nasal", it is merely the vibrations in the buccopharyngeal resonator giving a false sense of nasality. Miller comments that well-balanced timbre without nasality is often confused with a nasal timbre, and the existence of nasality can be effectively measured in the way the interviewee's described, but it can be measured even more efficiently with a device called the nasometer.22 The term "overtones" relates to the perception of a nasal timbre, and is a term often referred to in the description of the Bulgarian voice. Miller comments:

Singers and singing teachers have always known that prefacing sung phonation with nasals assists in adjusting the resonator tract for subsequent vowel sound. This is because the nasals tend to have acoustic strength in regions of the harmonic spectrum that are similar in distribution to the harmonic-partial distribution (overtones) found in the well-balanced spectrum of the singing voice. This balance is often popularly designated as "the ring of the voice."23

It seems that the Bulgarian voice is not nasal because it is likely that the vocal style incorporates a closed velopharyngeal port, but intense vibration in the buccopharyngeal resonator creates a timbre similar to nasality, which is further intensified by the distribution of harmonic partials in the voice causing a "ringing" sound.

The unique elements of the Bulgarian belt

The descriptions of belting previously discussed indicate that there is such a phenomenon as the "Bulgarian belt" at a scientific level and therefore an aural level, because many of the physiological actions of both styles are so similar. Based on my experiences of Bulgarian singing and other vocal styles incorporating belting, I have developed a list of the elements that distinguish the "Bulgarian belt" from other types of belting:

  • Vibrato is not incorporated except as ornamentation because the vocal folds during a sung phrase are constantly tight.
  • The Bulgarian timbre generally employs a constant intense belting sound whereas contemporary singers will incorporate different vocal qualities as well as belting such as "breathiness" - a whispered, speech-like quality; "head voice" (previously discussed); "falsetto" - a vocal quality that can arise in the upper register of the voice due to the vocal folds vibrating and only coming into contact at the free borders where the remainder of the folds stay firm and non-vibratory; and the use of the ventricular vocal folds or false folds - tissue in very close proximity to the true vocal folds that can clamp over the true folds if there is intense laryngeal tension and lack of efficient air flow. The effect of this is a growling, throaty timbre.
  • The Bulgarian language affects the timbre, as the Bulgarian vowels are forward closed vowels.
  • The Bulgarian sound is not nasal, whereas other types of belting often are.
  • There are higher overtones (which would be visible on a spectrogram) in Bulgarian singing due to the intense vibrations in the buccopharyngeal resonator and the forward vowel placement.
  • There are differences in ornamentation, although a lot of the ornamentation is very similar to a pop singer's melismatic line, and the yodels and yips can be heard in country music.
  • A smaller mouth shape is evident, and there is less mouth movement.

In the concluding chapter, a summary of the research presented will follow and the relevance and importance of research into integrating the areas of voice and ethnomusicology and possibilities of future research will be discussed.


(Links open in new window)

  1. G. Nair. 1999. Voice-tradition and technology, a state-of-the-art studio. California: Singular Publishing Group Inc., p. 35.
  2. R. Miller. 1996b. The structure of singing: System and art in vocal technique. New York: Schirmer Books, pp. 259-65.
  3. BlueCross BlueShield of Florida. 2002. "Body by sections - the chest". (Saturday 8 November 2003, 3:28pm), p. 1.
  4. Miller, 1996b. 265. (Miller's quotations).
  5. Lions voice clinic. "Anatomy and muscles of the larynx". (Saturday 8 November 2003, 3:11pm), p. 1.
  6. Lions voice clinic. "Anatomy of the larynx". (Saturday 8 November 2003, 3:11pm), p. 1.
  7. G. Nair. 1999. Voice-tradition and technology, a state-of-the-art studio. California: Singular Publishing Group Inc., pp. 35-41.
  8. Nair, 1999. p. 41.
  9. Supraglottic means literally "above the glottis", that is the space between the vocal folds.
  10. R. Miller. 1996a. On the art of singing. New York: Oxford University Press, p. 82.
  11. Miller, 1996a. p. 82.
  12. J. Estill. 1988. "Belting and classic voice quality: Some physiological differences." Medical problems of performing artists. 3: 38.
  13. A. Winter. 2003. "Belting for the female voice." (2 May 2003, 1:11pm).
  14. J. Estill. 1988. "Belting and classic voice quality: Some physiological differences." Medical problems of performing artists. 3: 38.
  15. R. Miller. 1996. The structure of singing: System and art in vocal technique. New York: Schirmer Books, p. 133.
  16. Lions voice clinic. "Intrinsic laryngeal muscles". (Saturday 8 November 2003, 3:11pm), p. 1.
  17. R. Edwin. 1998b. "The Bach to rock connection - Belting 101, part two." Journal of singing 55 (2): 61.
  18. R. Edwin. 1998a. "The Bach to rock connection - Belting 101." Journal of singing 55 (1): 53-5.
  19. R. Miller. 1996. The structure of singing: System and art in vocal technique. New York: Schirmer Books, p. 312.
  20. J. Estill. 1988. "Belting and classic voice quality: Some physiological differences." Medical problems of performing artists. 3: 42.
  21. Estill, 1988. 41-2.
  22. R. Miller. 1996c. "The velopharyngeal (palatopharyngeal) port during singing." Journal of singing 53 (1): 27.
  23. Miller, 1996c. 28.

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