Phonatory System Research Articles

The minimum glottal airflow to initiate vocal fold oscillation

Phonation threshold flow (PTF) is proposed as a new aerodynamic parameter of the speech production system in this study. PTF is defined as the minimum airflow that can initiate stable vocal fold vibration. Because the glottal airflow can be noninvasively measured, it is suggested that the aerodynamic parameter PTF may be more practical for clinical vocal disease assessment. In order to investigate the relationship between PTF and phonatory system properties, the stability of the body-cover vocal fold model was analyzed. The study has theoretically shown that PTF is a sensitive aerodynamic parameter dependent on tissue properties, glottal configuration, and vocal tract loading. It was predicted that PTF can be reduced by decreasing tissue viscosity, decreasing mucosal wave velocity, increasing vocal fold thickness, or decreasing prephonatory glottal area. Furthermore, it was predicted that a divergent glottis or low vocal tract resistance lead to a reduced PTF. Also discussed is the potential significance of PTF in investigating the energy distribution in a vocal fold vibration system and related clinical applications.

Voice acoustic patterns of patients diagnosed with vibroacoustic disease

BackgroundLong-term low frequency noise exposure (LFN) (≤500Hz, including infrasound) may lead to the development of vibroacoustic disease (VAD), a systemic pathology characterized by the abnormal growth of extra-cellular matrices. The respiratory system is a target for LFN. Fibrosis of the respiratory tract epithelia was observed in VAD patients through biopsy, and confirmed in animal models exposed to LFN. Voice acoustic analysis can detect vocal fold variations of mass, tension, muscular and neural activity. Frequency perturbation (jitter), amplitude perturbation (shimmer) and harmonicto- noise ratio (HNR) are used in the evaluation of the vocal function, and can be indicators of the presence and degree of severity of vocal pathology. Since the respiratory system is the energy source of the phonation process, this raises questions about the effects of VAD on voice production. The purpose of this study was to determine if voice acoustic parameters of VAD patients are different from normative data. MethodsNine individuals (5 males and 4 females) diagnosed with VAD were recorded performing spoken and sung tasks. The spoken tasks included sustaining vowels and fricatives. The sung tasks consisted of maximum phonational frequency range (MPFR). Voice acoustic parameters analysed were: fundamental frequency (F0), jitter, shimmer, HNR and temporal measures. ResultsCompared with normative data, both males and females diagnosed with VAD exhibited increased F0, shimmer and HNR. Jitter, MPFR and one temporal measure were reduced. ConclusionsVAD individuals presented voice acoustic parameter differences in spectral, temporal and perturbation measures, which may be indicative of small morphological changes in the phonatory system.

Pulmonary Function and Vocal Aerodynamics of Female Professional Sopranos and Nonsingers

PURPOSE: Singing requires exquisite coordination between the respiratory and phonatory system to efficiently control glottal airflow. Our study determines both pulmonary function and vocal aerodynamics in classically trained professional singers and compares the data obtained from singers with normal female subjects who had had no professional vocal training.

Considerations about teachers' dysphonias

Introduction: The objective of this paper is to discuss the different etiologic factors that affect the appearance and evolution of teachers' dysphonias, as well as to establish the main objectives of treatment. Material and Method: We considered 772 elementary and high school teachers, and evaluated their personal backgrounds, general clinical examination, psychological and audiological studies, phonatory system and environmental condition of the workplace. Results: We found that the most common pathology was the functional dysphonia or phonastenia, which is due among other factors to a functional breathing asynergy, while we detected few incidences of organic dysphonias. Discussion: This study discusses the different causes of dysphonia, especially the personal and institutional, and furthermore points out the specific labor disability and moral damage that generate in teachers, especially for women. Conclusions: Different measures for preserving and recuperating the teacher's voice in formative, such as professional, stages are proposed, and of special note is that the teacher must be considered a voice professional.

Parameters of phoniatric examinations for solo singers

A phoniatrist analyzes the professional's voice at the beginning of his vocal studies or career but also later, in cases of voice disorder. Phoniatric examination of professional singers must be done according to "all inclusive" protocols of examination. Such protocols must establish the status of basic elements of phonatory system: activator, generator and resonator of voice and articulatory space. All patients requiring phoniatric examination no matter if they are candidates for professional singers, need to provide anamnestic data about their previous problems regarding voice or singing. This examination is necessary and it must include: examination of nose, cavum oris, pharynx, ears and larynx. This analysis is based on evaluation of physiological and pathophysiological manifestations of voice. Determination of musical voice range during phoniatric examination does not intend to make any classification of voice, nor to suggest to vocal teacher what he should count upon from future singers. Musical range can be determined only by a phoniatrist skilled in music or with musical training, but first of all vocal teacher. These methods are used for examination of phonatory function, or laryngeal pathology. They are not invasive and give objective and quantitative information. They include: laryngostroboscopy, spectral analysis of voice (sonography) and fundamental parameters of voice signal (computer program). Articulation is very important for solo singers, because good articulation contributes to qualitative emission of sound and expression of emotions. Tonal-threshold audiometry is performed as a hearing test. They include rhinomanometry, vital capacity measurements, maximal phonation time and phonation quotient. Phoniatric examination is a necessary proceeding which must be performed before admission to the academy of solo singing, and then during singers' education and career. The phoniatric protocol must include a minimal number of parameters, which can be increased if required. All parameters of phoniatric examination must be adequately evaluated by experts.

Speech Science: An Integrated Approach to Theory and Clinical Practice

Speech Science: An Integrated Approach to Theory and Clinical Practice

VOCAL FOLD PHYSIOLOGY

This article examines the physiologic factors responsible for the production of phonation in humans. The article begins with an explanation of the control mechanisms of phonation and theories of vocal fold vibration. The physiologic concepts are based on the myoelastic-aerodynamic, body-cover, and mucosal wave theories. An evaluation of the cover-body theory is explained in terms of pitch control. The factors that regulate the vocal folds to produce pitch changes, intensity variation, and register effects are outlined. The changes in pitch, intensity, and voice qualities are related to the vocal fold mass, tension, subglottic pressure, and airflow generated by the phonatory systems. A brief summary of abnormal voice production is given in terms of disordered physiology and the emerging theory of chaos.

Relationship between aerodynamic measures of glottal efficiency and stroboscopic findings in asymptomatic singing students

Singing requires exquisite coordination between the respiratory and phonatory systems to efficiently control glottal airflow. Asymptomatic singing students underwent pulmonary function testing (PFT), videostrobolaryngoscopic examination, and measures of glottal efficiency (maximum phonation time [MPT], glottal flow rate [GFR], and phonation quotient [PQ]) performed in both a sung and spoken tone. Pulmonary function and glottal efficiency values were within reported normative data for professional singers. However, sung tones were made with significantly higher GFR and PQ and lower PQ than spoken tones. The mean GFR was not related to the degree of glottal closure (by videostrobolaryngoscopy) or underlying pulmonary support.

Acoustic loading exercises in singing training

Singing teachers have devised vocal exercises that present variable acoustic loads to the sound source. These exercises consist of lip and tongue trills, nasal consonants, and vowels with small mouth openings (like /u/). Some pedagogues and clinicians have advocated phonating into long and narrow tubes. Since none of these exercises produce either a strong or aesthetically pleasing acoustic output in and of themselves, their merit must lie in facilitating the respiratory and phonatory systems. Recent Hopf bifurcation analysis has shown that inertive acoustic loads, resulting from deliberate constricting and lengthening of some portion of the vocal tract, can lower the oscillation threshold pressure, thereby facilitating the ease of vocal onset. Resistive acoustic loads, either upstream or downstream of the vocal folds, have a less beneficial effect on oscillation threshold pressure. [Work supported by Grant No. P60 DC00976 from the National Institute on Deafness and Other Communication Disorders.]

Recent advances in monitoring techniques for speech production

In recent years, various techniques have been developed for monitoring the dynamics of articulatory and phonatory systems. For the articulatory system, x-ray, ultrasound, magnetic field, etc., have been utilized. Among them, MRI is most preferable because of high spatial resolution and safety, though it has to be supplemented by other techniques due to its limited temporal resolution. Recent results on tagged MRI of the tongue will be discussed. For the phonatory system, high-speed monitoring of vocal fold vibration is quite important in the study of voice production in normal as well as in pathological cases. A high-speed imaging technique up to 9000 frames per second has been developed, and is being used in this laboratory for recording fiberscopic images of the vocal fold vibration during running speech, singing, and other vocal activities. Aerodynamic measurement is also important for studying various modes of phonation. The difficulty of measuring the transglottal pressure is being overcome by the use of a miniaturized pressure transducer which can be inserted into the subglottic space. These new techniques provide a lot of new data as well as allow new interpretation of already existing data.

Social Environment and Incidence of Voice Disturbances in Children

The incidence of voice disturbances was investigated in children living under different social environments. Two groups of children at the age of 12-13 years were examined, with a total number of 362 examinees. The first study group consisted of children living in a rural environment (204 examinees) and the second group consisted of children from an urban area (158 examinees). The state of the voice and phonatory system was investigated, revealing 3.92% of children with voice problems within the rural group and 43.67% within the city group. The influence of the social environment is discussed, and also the need for behavior modification to be included in voice therapy.

声帯ポリープと早期声門癌における発声機能の比較

Aerodynamic parameters during optimal easy phonation were compared among 6 patients with vocal polyps, 32 patients with glottic cancer (T1 and T2) and 9 normal subjects.Subglottal pressures (cmH2O) directly extracted by the miniatured pressure tranceducer through the glottis, mean air flow (ml/sec), pitch (Hz) and intensity (dB) of voices, glottal resistance (cmH2O/l/sec), subglottal power (×106 erg/sec), and laryngeal efficiency were obtained with the use of PS-77phonatory equipment and the computerized phonatory system PI-100.The cases with vocal polyps presented with slightly high values of mean subglottal pressure (the mean value of 9.0cmH2O) and glottal resistance (the mean value of 38.5cmH2O/l/sec) and glottal power 3 times greater than that of the normal subjects. The mean value of laryngeal efficiency was about a half level of that in the normal subjects. In the cases of glottic cancer, the subglotal pressures were inceased to the mean value of 11.6 cmH2O in Tla, 21.7cmH2O in Tlb and 25.7cmH2O in T2 cases respectively. The Glottal resistance and subgottal power were significantly increased by as the T stage became advanced. In contrast, the laryngeal efficiencies decreased as the T stage was advanced : the mean value of 1.27 in T1a, 0.50 in T1b, and 0.25 in T2 cases.

Acoustic and physiological study of traditional Japanese singing

Acoustic and physiological characteristics of four genres of traditional Japanese singing were extracted. Subjects were professional singers of each genre: Sohkyoku, Yohkyoku, Minyoh, and Kyogen. Audio and video-fiberseopic recordings were made, while the singers were producing the singing voice of some typical phrases of their singing modes and the speaking voice as well. EGG recording was also made for a singer of Kyogen. Spectral analyses revealed prominent peaks at 4–4.5 kHz in the subject's singing voice, implying an evidence for the “singing formant” of traditional Japanese singing. Acoustic characteristics of the peculiar tone ornament suggest that the singers controlled F0 and intensity independently. Fiberscopic observation of the vocal tract and EGG signals provided some physiological bases to understand the singers' fine control of the phonatory system for such specific voice production.

Relationships Between Selected Auditory and Phonatory Latency Measures in Normal Speakers

Interaction between auditory and phonatory systems was explored in normal speakers by comparing laryngeal reaction time (LRT) with interpeak intervals from the auditory brainstem response (ABR) obtained using high and low stimulus presentation rates. Thirty-four subjects with no history of neurological or speech-language disorders and normal hearing sensitivity participated. Interpeak intervals were derived from ABR's recorded for each ear at rates of 21.1 and 91.1 clicks/s. LRT responses were obtained by instructing subjects to sustain an /s/ and then phonate an /a/ as fast as possible following visual cues. Two measures of reaction time performance were derived, Mean Laryngeal Reaction Time (MLRT) and Best Laryngeal Reaction Time (BLRT). Linear regression analyses were completed between each measure of reaction time performance and each ABR interpeak interval. Using either LRT measure, two significant (p less than .05) positive linear relationships were found. One involved the interpeak interval between Waves III and V and the other involved the interpeak interval between Waves I and V. Both were recorded at high stimulus presentation rates. These results support the small body of literature from normal speakers, stutterers, and spasmodic dysphonics suggesting interaction between the auditory and phonatory systems at the brainstem level.

Development of oral-motor skills in the neurologically impaired child receiving non-oral feedings

Treatment of children with swallowing dysfunction requires a holistic approach based on a global view of their problems and needs. The connection of the swallowing mechanism with the sensorimotor organization of postural tone and movement throughout the body is a critical factor in the evaluation and treatment of children whose dysphagia is rooted in a neurologic disorder. An appropriate program includes work with the development of movement skills, sensory processing, learning, social skills, and communication. The initial focus is placed on oral-motor treatment, rather than direct work on oral feeding. The primary goal of the program is to develop the appropriate use of the mouth, respiratory, and phonatory systems in exploration, sound play, and as much oral feeding as possible. Oral feeding is the by-product of a total program, not its major goal.

Studies in Parkinson's Disease: I. Perceptual Speech Analyses

The perceptual speech characteristics of a group of 19 subjects with mild-moderate Parkinson's Disease (PD) were compared with those of a normal non-neurologically impaired control group matched for age and sex. Deficits were found in all aspects of speech production, including respiration, phonation, prosody, articulation and resonance. Observed speech deviations were most often mild. The speech deviation which contributed most to the variance in overall intelligibility of speech was imprecision of consonant articulation. Deficits in the phonatory system, including the presence of hoarseness and a strained strangled phonation with intermittent breathiness, were found to be the frequently occurring speech deviations in PD. Disturbed prosodic features were also noted, including a disturbed general stress pattern and a lack of variation in both pitch and loudness levels. The need for careful instrumentally based assessments of the physiological and acoustic features of hypokinetic dysarthria is emphasized.

Selective impairment of phonation: A case study

A 47-year-old right-handed man underwent craniotomy for clipping of an aneurism at the trifurcation of the left middle cerebral artery. Subsequently, he suffered a left hemisphere CVA after which his speech and language resembled that of Broca's aphasia with accompanying apraxia of speech. Medical, behavioral, and acoustical data amassed over a period of several months indicated numerous contraindications to traditional diagnoses of Broca's aphasia, apraxia of speech, and dysarthria. Ultimately, it was determined that the patient had a selective impairement of phonation or laryngeal apraxia. This was illustrated dramatically when he was taught to use an electrolarynx which allowed him to bypass his disrupted phonatory system. Speaking with the electrolarynx, the patient communicated normally. Any semblance of Broca's aphasia disappeared. Supralaryngeal articulation was normal; apraxia of speech behaviors were absent. This case report indicates that dissociation of oral and laryngeal gestures due to brain injury is possible. Mechanisms underlying such a dissociation for this case are reviewed. The possibility of discrete center lesions in the frontal motor association area causing different types of apraxia of speech is discussed.

Study of subglottal air pressure during Hindi stop consonants.

This study examines subglottal air pressure (Ps) variations in Hindi stop consonants. The stops were produced in initial, medial and final positions and under different stress conditions in nonsense utterances of the type CV, VCV and VC which were embedded in a frame sentence. The results show no systematic correlation between Ps variations during the oral closure of the stops and the voicing and/or aspiration contrasts associated with them. However, aspiration and a momentary drop in Ps immediately after the release of aspirated stops seem to be systematically related. A systematic relationship between a momentary increase in Ps and production of stress is also observed. The variations in Ps associated with the production of stop consonants appear to be reflections of the changes in the glottal and supraglottal impedances. Ps variations related to normal stress appear to be controlled by the phonatory system rather than the respiratory system. On the other hand, for the implementation of heavy or emphatic stress, the phonatory and the respiratory systems appear to function synergistically.

Recurrent layngeal nerve section for spasmodic dysphonia.

Spasmodic dysphonia is a severe disorder of phonation accompanied by extreme tension of the entire phonatory system. The expressive functions of speech such as laughter, singing, and whispering are much less affected if at all. Psychotherapy, speech therapy, stimulant and psychotropic drugs, hypnotism and acupuncture have all been tried as treatment without success. In 1976, Dedo reported 34 patients who were managed with recurrent laryngeal nerve section for spasmodic dysphonia. All of these patients had marked improvement in voice with relief of spasticity. Twenty-two patients with documented spasmodic dysphonia present for at least one year have been managed at the Cleveland Clinic since Dedo's report. None of them had any improvement with conventional voice therapy and were subjected, therefore, to recurrent laryngeal nerve section.

From discrete linguistic units to continuous speech characteristics—a functional formulation of articulatory and phonatory dynamics

Formulation of the process of conversion from discrete linguistic units to the continuous acoustic characteristics of speech and vice versa is crucial to both speech synthesis by rule and automatic speech recognition. This paper will present a review of recent works on this problem, with an emphasis on the functional modeling of the processes whereby the segmental and suprasegmental features of speech are realized through the dynamic control of the articulatory and the phonatory systems. The trajectories of acoustic or articulatory parameters of speech are to be interpreted as consequences of the control of the articulatory system by a sequence of discrete phonemic commands, while the trajectory of the voice fundamental frequency is to be regarded as a consequence of the control of the phonatory system by a sequence of discrete prosodic commands. Speech analysis and synthesis based on these models are shown to lead to a better understanding of the dynamic processes of speech production. [Work supported by Ministry of Education Grant‐in‐Aid for Scientific Research No. 239005.]