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Professional voice users such as singers and teachers are at high risk for vocal injury. A literature review was conducted to understand the prevalence of voice problems and the effectiveness of vocal hygiene education. The findings of the review suggested that in order to reduce the impact of voice disorders, it is imperative that the education of singers and teachers include how the voice functions and how to best take care of it. The purpose of this study was to discover what students on a collegiate level know about vocal anatomy, physiology, and vocal hygiene issues. It was hypothesized that graduate students who had taken a pedagogy course, were more knowledgeable about vocal anatomy, physiology, and vocal health than undergraduate or graduate students who had not had such a course. A survey was administered to voice students at a large university music program to ascertain the level of student knowledge. An analysis of the survey results provides educators with insight into specific areas of student deficiency and current collegiate pedagogical needs. The findings from the study survey were applied to recommendations for undergraduate and graduate vocal pedagogy curriculum, with an emphasis on anatomy, physiology, and preventative care of the voice. Course descriptions, objectives, and assessment methods were included for each vocal pedagogy course. The study recommended that all voice students receive information that allows them to make educated decisions regarding voice care and prepares them to be leaders in teaching singing based on voice science. In addition to anatomy and physiology of the voice, vocal hygiene is an important topic to be included in pedagogy curriculum. Issues and resent research in vocal hygiene were discussed including: speaking habits, hydration, reflux, medical management, etc. and how these contribute to or detract from efficient voice use.

While a limited body of research pertaining to vocal sound quality exists, technological advances in sound analyses have facilitated a reexamination of vocal timbre. The sound quality of sung vowels ([ a], [e ], C i ]) produced by ten baritone/bass singers at the University of North Texas was analyzed by the use of Fourier analysis and electronic digital equipment. This procedure and equipment produced results over a wider frequency range with greater accuracy than prior studies on vocal timbre. The study sought to answer the following questions: (1) Using formant regions between 0-20 kHz for comparison, what similarities and differences can be observed among spectra produced from [a], [e], and [ i ] vowels sung by baritone/bass singers? (2) Using formant regions between 0-20 kHz for comparison, what similarities and differences can be observed among spectra produced from [a], [ e ], and [ i ] vowels sung by baritone/bass singers with regard to individual singers? (3) Approximately what vocal-tract tube lengths were used by baritone/bass singers when performing [a], [e ], and [ i ] vowels? (4) What similarities in vocal-tract tube lengths can be generalized as to [ a], L e ], and [ i ] vowels sung by individual baritone/bass singers? The results of the study suggested that: (1) Below approximately 4 kHz formant frequency location can be generalized by a specific vowel between subjects. (2) Above 4 kHz the generalization of formant frequency location is difficult between subjects singing the same vowels, but general frequency location for formants can be identified between samples produced by the same singer performing different vowels. (3) Subjects did alter their vocal-tract lengths as different vowel sounds were performed, but no overall pattern of tube length with reference to specific vowels was indicated. (4) Each singer did use a unique vocal-tract length. The average estimated vocal-tract length for all subjects singing a specific vowel revealed little variation in tube length with an average tube length of 278.97 mm.

Straw phonation is a semi-occluded vocal tract exercise (SOVTE) that has long been used as a therapeutic device for the voice. The purpose of this study was to compare outcomes following voice lessons that included a straw phonation protocol to those that did not include a protocol. The primary outcome measures were the shortened version of the Singing Voice Handicap Index (SVHI-10), which is a validated health status instrument for singers, and Perceived Vocal Efficiency (PVE). Ten student singers in a large college of music consented into the study and participated in both lesson conditions, serving as their own control. They completed six voice lessons over a six week period with lessons alternating between the straw phonation protocol and no straw phonation protocol conditions. Outcome measures were collected following all six lessons. Repeated measures one-way analysis of variance (RM-ANOVA) revealed no statistically significant effect of the straw phonation protocol on either dependent variable. However, a small effect was found for PVE, indicating that straw phonation led to a perceived improvement in vocal efficiency. There was significant variation in individual responses to straw phonation and participants who had more prior experience with the SOVT experienced less perceptual change across lesson conditions. Most singers reported finding straw phonation a useful addition to their voice lesson and felt it improved their vocal efficiency. These results indicate that straw phonation could be regularly integrated into voice lessons and may be most helpful to students who find the SOVTE worthwhile. Future studies should examine the effects of a similar protocol using multiple SOVTEs, tailored to what is most efficacious for individuals, and should use a separate control group.

La parole et le chant ont une importance capitale dans la culture humaine. Cependant les phénomènes physiques de production et de contrôle de la voix sont encore mal compris, et leurs paramètres mal connus, principalement en raison de la difficulté d'y accéder in vivo. Dans le modèle source-filtre simplifié, la source sonore est produite par l'oscillation des plis vocaux à une fréquence fondamentale et ses multiples ; les résonances du conduit vocal filtrent l'enveloppe spectrale du signal pour produire des voyelles. Dans cette thèse, les propriétés de la source et du filtre sont étudiées et une expérience in vitro examine l'influence du filtre sur la source. L'influence des paramètres de contrôle aérodynamiques ou mécaniques sur la fréquence fondamentale est étudiée ex vivo en utilisant des larynx humains excisés. Quatre types de discontinuités ou d'hystérésis sont observés. En dehors de ces zones de bifurcation, la fréquence fondamentale est approximativement proportionnelle à la racine carrée de la pression sous-glottique, ce qui a des implications pour le chant et de la parole, en particulier dans les langues tonales. De plus, le flux d'air qui traverse la glotte provoque un rétrécissement du conduit aryépiglottique sous l'effet de forces de pression aérodynamique, et peut initier l'oscillation des plis ventriculaires et/ou aryépiglottiques sans contrôle musculaire. L'impédance acoustique de conduits vocaux fut mesurée in vivo sur un intervalle de9 octaves en fréquence et de 80 dB en amplitude, avec la glotte fermée puis pendant la phonation. Les fréquences, amplitudes et largeurs de bande des résonances acoustiques et des résonances mécaniques des tissus autour du conduit vocal sont estimées. Lorsque la glotte est fermée, les largeurs de bande et les pertes d'énergie correspondantes dans le conduit vocal sont largement supérieures aux pertes viscothermiques d'un cylindre rigide lisse, et sont encore plus importantes pendant la phonation. En utilisant un modèle simple de conduit vocal et les mesures effectuées en inspirant, des résonances acoustiques du système sous-glottique sont également estimées. Les effets possibles de la charge aéroacoustique du filtre sur la source sont mis en évidence dans une expérience sur une maquette de plis vocaux constituée de boudins de latex remplis d'eau couplés à un tuyau rigide. La modification de la charge acoustique en aval des plis vocaux, par insertion d'une paille à l'extrémité du conduit, modifie la fréquence fondamentale de vibration des plis. Ce résultat est discuté dans le contexte des méthodes de rééducation orthophonique à la paille couramment utilisées en thérapie de la parole. / Speech and singing are of enormous importance to human culture, yet the physics that underlies the production and control of the voice is incompletely understood, and its parameters not well known, mainly due to the difficulty of accessing them in vivo. In the simplified but well-accepted source-filter model, non-linear vocal fold oscillation produces a sound source at a fundamental frequency and its multiples, the resonances of the vocal tract filter the spectral envelope of the sound to produce voice formants. In this thesis, both source and tract properties are studied experimentally and an in vitro experiment investigates how the filter can affect the source. The control of fundamental frequency by either air supply or mechanical control parameters is investigated ex vivo using excised human larynges. All else equal, and excluding the four types of discontinuity or hysteresis observed, the fundamental frequency was found to be proportional to the square root of subglottal pressure, which has implications for singing and speech production, particularly in tonal languages. Additionally, airflow through the glottis causes a narrowing of the aryepiglottic tube and can initiate ventricular and/or aryepiglottic fold oscillation without muscular control. The acoustic impedance of the vocal tract was measured in vivo over a range of 9 octaves and 80 dB dynamic range with the glottis closed and during phonation. The frequencies, magnitudes and bandwidths were measured for the acoustic and for the mechanical resonances of the surrounding tissues. The bandwidths and the energy losses in the vocal tract that cause them were found to be five-fold higher than the viscothermal losses of a dry, smooth rigid cylinder, and to increase during phonation. Using a simple vocal tract model and measurements during inhalation, the subglottal system resonances were also estimated. The possible effects of the filter on the source are demonstrated in an experiment on a water-filled latex vocal fold replica: changing the aero-acoustic load of the model tract by inserting a straw at the model lips changes the fundamental frequency. This result is discussed in the context of straw phonation used in speech therapy.

The Voice Foundation Vocal fatigue is a frequent symptom and a debilitating condition affecting individuals with voice disorders. In spite of the various attempts to define and quantify vocal fatigue, this complex trait has not been well understood. Mokken scaling was performed on the Vocal Fatigue Index (VFI) to develop a hierarchical understanding of the latent trait of vocal fatigue. Two hundred nine patients with voice disorders completed the VFI and provided the item responses necessary to complete the Mokken scaling. Results revealed a moderately strong Mokken scale and that the VFI presents a hierarchical structure to the underlying trait of vocal fatigue. Mokken scaling contributes to the ongoing investigation to the underlying construct of vocal fatigue and may provide additional information about specific complaints within the population of those with voice disorders.

Communication by voice is foundational in our society and many rely on their voices for their occupations. Voice disorders affect a significant number of individuals each year, and diagnosis and treatment improvements are therefore sought via advancements in voice research. Contained in this thesis is a description of work intended to contribute to vocal fold research by using synthetic, self-oscillating vocal fold replicas to study the impact of replica vibration on perfusion fluid flow through the replica. Methods for manufacturing vocal fold replicas containing imbedded channels allowing for fluid perfusion are discussed. Experimental procedures developed for delivering perfusion fluid to the imbedded channel at a constant pressure during replica vibration are described. Methods for measuring perfusion parameters of perfusion fluid pressure, imbedded channel diameter, flow rate, and vibration parameters (subglottal pressure, frequency, amplitude, channel length, and glottal width) are detailed. Experiments performed using both stationary and vibrating vocal fold replicas are presented. Correlations between perfusion pressure and channel diameter are discussed. Vibration parameters were correlated to perfusion flow parameters and it is shown that perfusion flow rate through the channels decreased significantly with model vibration. Potential mechanisms for changes in perfusion flow resistance with vibration are discussed and analyzed. Output of a theoretical model, developed to incorporate some of the possible flow resistance mechanisms, was compared to vibrating replica experimental data.

Este trabalho é fruto de uma pesquisa-ação associada às atividades de preparação vocal realizadas com o Coral Escola e o Coral Oficina do Comunicantus: Laboratório Coral do Departamento de Música da ECA-USP. Os objetivos dividiram-se em duas perspectivas: a formação do estagiário em preparação vocal e o desenvolvimento da técnica vocal nos coros Escola e Oficina. A coleta de dados foi feita por meio da participação nos ensaios destes dois grupos no ano de 2010 e da análise do protocolo de documentação do Comunicantus: Laboratório Coral. O capítulo 1 inicia-se com uma explanação sobre o funcionamento do Comunicantus: Laboratório Coral e sobre o conceito de Coral Escola, no qual todas as atividades estão fundamentadas; segue com uma discussão a respeito dos desafios da educação coral no século XXI e encerra-se expondo saberes e habilidades que fazem parte da formação dos estagiários em preparação vocal, como a classificação vocal, a percepção vocal e a pedagogia. No capítulo 2, são descritas as principais características vocais dos coralistas iniciantes dos coros Escola e Oficina em relação a postura, respiração, apoio, ressonância, articulação, assim como as dificuldades mais frequentes com afinação. No capítulo 3, por meio de uma confrontação entre as práticas do Comunicantus: Laboratório Coral e a literatura sobre regência coral e pedagogia vocal, são apresentados e discutidos os exercícios mais usados na preparação vocal destes grupos, visando trabalhar aspectos como postura, respiração e apoio, ressonância, diferenciação de vogais, agilidade, staccato, sustentação, homogeneidade de registros vocais, extensão e escuta harmônica. Nas considerações finais, discute-se a perspectiva da preparação vocal como uma atividade complexa, na qual diversos saberes, habilidades e ferramentas são empregados conjunta e interativamente como parte de estratégias que visam à consecução de objetivos artísticos e educativos. / This work is the result of an action research associated to voice building activities performed at the Coral Escola and the Coral Oficina of Comunicantus: Choral Laboratory of the Music Department at ECA-USP. The goals were divided into two perspectives: the training of the trainee in voice building and the development of vocal technique in the choirs Escola and Oficina. Data collection was done through participation in the rehearsals of these two choirs in 2010 and analysis of Comunicantus: Choral Laboratory\'s protocol documentation. Chapter 1 begins with an explanation about the functioning of Comunicantus: Choral Laboratory and about the concept of Choir-School, in which all activities are based; it follows with a discussion about the challenges of choral education in the twenty-first century and it ends exposing knowledge and skills that are part of the training of trainees in voice building, such as vocal classification, vocal perception and pedagogy. Chapter 2 describes the main vocal characteristics of the beginners in the choirs Escola and Oficina regarding posture, breathing support, resonance, articulation, as well as the most frequent difficulties concerning intonation. By confronting the practices of Comunicantus: Choral Laboratory and the literature on choral conducting and vocal pedagogy, Chapter 3 presents and discusses the most used exercises in the voice building activities of these groups, aiming to work aspects such as posture, breathing and support, resonance, vowel differentiation, agility, staccato, sostenuto,homogeneity of vocal registers, extension and harmonic hearing. In the final considerations, voice building is discussed as a complex activity, in which different knowledge, skills and tools are used together and interactively as part of strategies that aim the achievement of artistic and educational goals.

Este trabalho é fruto de uma pesquisa-ação associada às atividades de preparação vocal realizadas com o Coral Escola e o Coral Oficina do Comunicantus: Laboratório Coral do Departamento de Música da ECA-USP. Os objetivos dividiram-se em duas perspectivas: a formação do estagiário em preparação vocal e o desenvolvimento da técnica vocal nos coros Escola e Oficina. A coleta de dados foi feita por meio da participação nos ensaios destes dois grupos no ano de 2010 e da análise do protocolo de documentação do Comunicantus: Laboratório Coral. O capítulo 1 inicia-se com uma explanação sobre o funcionamento do Comunicantus: Laboratório Coral e sobre o conceito de Coral Escola, no qual todas as atividades estão fundamentadas; segue com uma discussão a respeito dos desafios da educação coral no século XXI e encerra-se expondo saberes e habilidades que fazem parte da formação dos estagiários em preparação vocal, como a classificação vocal, a percepção vocal e a pedagogia. No capítulo 2, são descritas as principais características vocais dos coralistas iniciantes dos coros Escola e Oficina em relação a postura, respiração, apoio, ressonância, articulação, assim como as dificuldades mais frequentes com afinação. No capítulo 3, por meio de uma confrontação entre as práticas do Comunicantus: Laboratório Coral e a literatura sobre regência coral e pedagogia vocal, são apresentados e discutidos os exercícios mais usados na preparação vocal destes grupos, visando trabalhar aspectos como postura, respiração e apoio, ressonância, diferenciação de vogais, agilidade, staccato, sustentação, homogeneidade de registros vocais, extensão e escuta harmônica. Nas considerações finais, discute-se a perspectiva da preparação vocal como uma atividade complexa, na qual diversos saberes, habilidades e ferramentas são empregados conjunta e interativamente como parte de estratégias que visam à consecução de objetivos artísticos e educativos. / This work is the result of an action research associated to voice building activities performed at the Coral Escola and the Coral Oficina of Comunicantus: Choral Laboratory of the Music Department at ECA-USP. The goals were divided into two perspectives: the training of the trainee in voice building and the development of vocal technique in the choirs Escola and Oficina. Data collection was done through participation in the rehearsals of these two choirs in 2010 and analysis of Comunicantus: Choral Laboratory\'s protocol documentation. Chapter 1 begins with an explanation about the functioning of Comunicantus: Choral Laboratory and about the concept of Choir-School, in which all activities are based; it follows with a discussion about the challenges of choral education in the twenty-first century and it ends exposing knowledge and skills that are part of the training of trainees in voice building, such as vocal classification, vocal perception and pedagogy. Chapter 2 describes the main vocal characteristics of the beginners in the choirs Escola and Oficina regarding posture, breathing support, resonance, articulation, as well as the most frequent difficulties concerning intonation. By confronting the practices of Comunicantus: Choral Laboratory and the literature on choral conducting and vocal pedagogy, Chapter 3 presents and discusses the most used exercises in the voice building activities of these groups, aiming to work aspects such as posture, breathing and support, resonance, vowel differentiation, agility, staccato, sostenuto,homogeneity of vocal registers, extension and harmonic hearing. In the final considerations, voice building is discussed as a complex activity, in which different knowledge, skills and tools are used together and interactively as part of strategies that aim the achievement of artistic and educational goals.