Vocal tract area functions and formant frequencies in opera tenors' modal and falsetto registers

According to recent model investigations, vocal tract resonance is relevant to vocal registers. However, no experimental corroboration of this claim has been published so far. In the present investigation, ten professional tenors' vocal tract configurations were analyzed using MRI volumetry. All subjects produced a sustained tone on the pitch F4 (349 Hz) on the vowel /a/ (1) in modal and (2) in falsetto register. The area functions were estimated from the MRI data and their associated formant frequencies were calculated. In a second condition the same subjects repeated the same tasks in a sound treated room and their formant frequencies were estimated by means of inverse filtering. In both recordings similar formant frequencies were observed. Vocal tract shapes differed between modal and falsetto register. In modal as compared to falsetto the lip opening and the oral cavity were wider and the first formant frequency was higher. In this sense the presented results are in agreement with the claim that the formant frequencies differ between registers.     

MRI Anatomical and Morphological Differences in the Vocal Tract Between Dysphonic and Normal Adult Women

Objective

To analyze the vocal tract morphometry of women with vocal nodules (VN) compared with normal subjects by means of magnetic resonance imaging (MRI) at rest position.

Study Design

Prospective study.

Methods

The present research included 20 young adult women, aged 18–40 years: 10 dysphonic patients with VN and 10 normal subjects. All participants were tested using MRI; 12 measurements of the vocal tract were performed: nine in median sagittal section and three in axial section.

Results

The 12 measurements were smaller in the dysphonic group; statistical significance was obtained for three parameters: in the sagittal plane, the laryngeal vestibule area was significantly smaller in the dysphonic group, with P = 0.012∗ (∗ = statistical significance); in the axial section, the distance between the right and left vocal processes of the arytenoids’ cartilages and the distance between the anterior commissure of the glottis and the laryngeal posterior wall were also significantly lower in the dysphonic group, with P = 0.036∗ and 0.010∗, respectively. Significant differences in the vocal tract morphometry of individuals with VN were observed compared with normal subjects, at rest position.

Conclusions

Results obtained from this study suggest that patients with VN may present a constantly increased tension of the laryngeal muscles, even at rest; moreover, reduced anterior-posterior dimension of the larynx may be a morphological characteristic of patients with VN.     

Some physical characteristics of the male falsetto voice

Previous research indicated that, as groups, male (bass/baritone) and female (soprano) professional singers tend to exhibit differing vocal tract and voice source behaviours. The use of an objective measure of voice [xeroradiographic-electrolaryngographic analysis (XEL)] revealed differences between the two voice types, especially at the highest sample pitches (e, 330 Hz for bass/baritones, and e″, 1,320 Hz for sopranos). XEL analysis combines two known techniques, i.e., soft-tissue radiographic imaging (xeroradiography), and an analysis of voice-source vibratory patterning (electrolaryngography). Subsequent to this investigation, interest centered on the male professional falsetto voice over a two-octave range (E 165 Hz to e′ 660 Hz) using a sample (n=9) of professional countertenors. Results suggest that there are characteristic trends in the patterning of the male professional falsetto register, but there is also evidence of within-group variability. The subjects significantly increased the size of the pharyngeal tube area during phonation. ANOVA and Trend Analysis revealed ventricular space as the only measure to expand systematically and consistently as sung pitch increases.     

Bacterial Cellulose as Laryngeal Medialization Material: An Experimental Study

Hypothesis

The use of a material made of bacterial cellulose with the aim of obtaining vocal fold medialization has not hitherto been fully investigated. Although the material has been tested in other animal models, the evaluation did not include the larynx; hence, situations, such as tissue reaction, material absorption, and extrusion, need to be addressed to evaluate its usefulness as a material for laryngeal reconstruction.

Objective

To evaluate the medialization, tissue response, and healing of rabbit vocal folds, after the implantation of a membrane of bacterial cellulose.

Study Design

Experimental study.

Methods

A total of 32 rabbits were used, two of which were used to check out the adequacy of the implant location. The animals were followed for 4 months and grouped according to follow-up times of 2, 4, and 16 weeks. All test animals received an implant of bacterial cellulose in one vocal fold and the injection of distilled water in the other, both performed by videoendoscopic cervicotomy. At the end of the follow-up, the presence of inflammatory and medial displacement was evaluated.

Results

No statistically significant difference in the inflammatory parameters between the study and control vocal folds or among follow-up times was found. All animals receiving cellulose presented medial displacement of vocal folds, and all retained this material at the implant site up to study endpoint.

Conclusion

Bacterial cellulose is a useful material for laryngeal medialization, showing no signs of rejection or absorption.     

The Impact of Voice Disorders Among Teachers: Vocal Complaints, Treatment-Seeking Behavior, Knowledge of Vocal Care, and Voice-Related Absenteeism

Objectives

Teachers are at increased risk for developing voice disorders. Occupational risk factors have been extensively examined; however, little attention has been paid to the consequences of the vocal complaints. The objective of this study was to investigate the knowledge that teachers have about vocal care, treatment-seeking behavior, and voice-related absenteeism.

Methods

The study group comprised 994 teachers and 290 controls whose jobs did not involve vocal effort. All participants completed a questionnaire inquiring about vocal complaints, treatment-seeking behavior, voice-related absenteeism, and knowledge about vocal care. Comparisons were made between teachers with and without vocal complaints and with the control group.

Results

Teachers reported significantly more voice problems than the control population (51.2% vs 27.4%) (χ² = 50.45, df = 1, P < 0.001). Female teachers reported significantly higher levels of voice disorders than their male colleagues (38% vs 13.2%, χ² = 22.34, df = 1, P < 0.001). Teachers (25.4%) sought medical care and eventually 20.6% had missed at least 1 day of work because of voice problems. Female teachers were significantly more likely to seek medical help (χ² = 7.24, df = 1, P = 0.007) and to stay at home (χ² = 7.10, df = 1, P = 0.008) in comparison with their male colleagues. Only 13.5% of all teachers received information during their education.

Conclusions

Voice disorders have an impact on teachers' personal and professional life and imply a major financial burden for society. A substantial number of teachers needed medical help and was obligated to stay at home because of voice problems. This study strongly recommends the implementation of vocal education during the training of teacher students to prepare the vocal professional user.     

Bifurcations and chaos in register transitions of excised larynx experiments

Experimental data from an excised larynx are analyzed in the light of nonlinear dynamics. The excised larynx provides an experimental framework that enables artificial control and direct observation of the vocal fold vibrations. Of particular interest in this experiment is the coexistence of two distinct vibration patterns, which closely resemble chest and falsetto registers of the human voice. Abrupt transitions between the two registers are typically accompanied by irregular vibrations. Two approaches are presented for the modeling of the excised larynx experiment; one is the nonlinear predictive modeling of the experimental time series and the other is the biomechanical modeling (three-mass model) that takes into account basic mechanisms of the vocal fold vibrations. The two approaches show that the chest and falsetto vibrations correspond to two coexisting limit cycles, which jump to each other with a change in the bifurcation parameter. Irregular vibrations observed at the register jumps are due to chaos that exists near the two limit cycles. This provides an alternative mechanism to generate chaotic vibrations in excised larynx experiment, which is different from the conventionally known mechanisms such as strong asymmetry between the left and right vocal folds or excessively high subglottal pressure.     

Augmentation of the Porcine Vocal Fold Using Autologous Composite Cervical Fascia and Fat Graft. Comparison Between the Transmuscular and Submuscular Approaches

Objectives

To assess the integration of an autologous composite fascia and fat graft implanted into the lamina propria of a porcine vocal fold using two different approaches.

Study Design

An experimental prospective study on the porcine larynx was conducted at a tertiary research institution.

Methods

An external cervical approach was used to expose the thyroid cartilage of 24 healthy minipigs under general anesthesia. The composite fascia/fat graft was implanted through two distinct approaches, transmuscular and submuscular. Animals were sacrificed at 7, 30, 90, and 180 days for macroscopic and histological study of the larynx. Graft integration and local inflammatory response were studied.

Results

The survival rate of the experimental model was 100% and all animals had local inflammatory response to the surgical procedure. Only 41.7% of the grafts placed inside the thyroarytenoid (TA) muscle fibers were identified postmortem, whereas 83.3% of the submuscular grafts remained intact.

Conclusions

Graft incorporation was better and there was less inflammation when the architecture of the TA muscle fibers was preserved. Graft extrusion was observed in the most of the cases where it was placed inside the muscle.     

Voice and Laryngeal Configuration of Men With Unilateral Vocal Fold Paralysis Before and After Medialization

Aim

To describe the laryngeal configuration and the voice of male patients diagnosed with unilateral vocal fold paralysis (UVFP) before and after medialization.

Methods

A retrospective study involving the collection of data from medical records of 142 patients diagnosed with UVFP from January 2003 to April 2009, submitted to auditory-perceptual assessment of voices and visual perception of laryngeal images before and after medialization.

Results

The study included data from 24 male patients, with an average of 60.7 years, who underwent three surgical medialization techniques (injection of hyaluronic acid, type I thyroplasty, and injection of Teflon). Before treatment, the position of the paralyzed vocal fold was seen to have a significant influence to the passing of the healthy vocal fold beyond the midline and on the overall degree of dysphonia. After treatment, the complete glottic closure; the free margin of the linear vocal fold; paralyzed vocal fold in the median position, reduction of hoarseness, roughness and breathiness (more frequently mild), and asthenia (more frequently normal and mild); tension and instability (more frequency normal); and a decrease in the overall degree of dysphonia were found to be significant.

Conclusion

The position of the paralyzed vocal fold influences the position of the healthy vocal fold in relation to the midline and the overall degree of dysphonia. All three treatments improved the glottic configuration and the voice of patients with UVFP.     

Voice Analysis of Postlingually Deaf Adults Pre- and Postcochlear Implantation

Objectives

To ascertain whether cochlear implantation (CI), without specific vocal rehabilitation, is associated with changes in perceptual and acoustic vocal parameters in adults with severe to profound postlingual deafness.

Hypothesis

Merely restoring auditory feedback could allow the individual to make necessary adjustments in vocal pattern.

Study Design

Prospective and longitudinal.

Methods

The experimental group composed of 40 postlingually deaf adults (20 males and 20 females) with no previous laryngeal or voice disorders. Participants’ voices were recorded before CI and 6–9 months after CI. To check for chance modifications between two evaluations, a control group of 12 postlingually deaf adults, six male and six female, without CI was also evaluated. All sessions composed of the recording of read sentences from Consensus Auditory-Perceptual Evaluation of Voice and sustained vowel /a/. Auditory and acoustic analyses were then conducted.

Results

We found a statistically significant reduction in overall severity, strain, loudness, and instability in auditory analysis. In vocal acoustic analysis, we found statistically significant reduction fundamental frequency (F0) values (in male participants) and F0 variability (in both genders). The control group showed no statistically significant changes in most vocal parameters assessed, apart from pitch and F0 (in female participants only). On comparing the interval of variation of results between the experimental and control groups, we found no statistically significant difference in vocal parameters between CI recipients and nonrecipients, with the exception of F0 variability in male participants.

Conclusions

The patients in our sample showed changes in overall severity, strain, loudness, and instability values, and reductions in F0 and its variability. On comparing the variation of results between the groups, we were able to prove in our study that implant recipients postlingually deaf adults (experimental group), without specific vocal rehabilitation, differed from nonrecipients (control group) in loudness and F0 variability sustained vowel /a/ in male participants.     

Voice Training and Changing Weight—Are They Reflected in Speaking Fundamental Frequency, Voice Range, and Pitch Breaks of 13-Year-Old Girls? A Longitudinal Study

Objective

Assessment of the voice-change progress of 20 girls (12–13 years) over 1 year by observing changes in speaking fundamental frequency (SFo), voice range, and register pitch breaks in the context of weight, height, voice training, and self-perception.

Study Design

One-year longitudinal collective case study.

Method

Twenty girls were recorded at the beginning and end of a year; nine girls were recorded another three times. SFo, vocal range, and characteristics were analyzed and interactions between these data assessed against weight and height to indicate pubertal development, and to test the hypothesis that changes in weight, height, SFo, and pitch breaks were related. Effects of training and the girls' self-perception of their voice use were also assessed.

Results

Vocal characteristics changed as the girls passed through different weight ranges. During 47.5–52.4 kg (called band 2) and 52.4–57.5 kg (band 3), there was progressive contraction of vocal range and in some girls a slight rise in SFo between recording times 1 and 5. Both high- and low-pitch breaks were present in 45% of girls' voices. Girls in band 4 (<57.5 kg) had an increased vocal range, and pitch breaks in vocal-range areas that indicated the development of adult vocal registers. In this study, voice-trained girls were heavier, had higher SFo, used wider speech-range inflection, had a higher vocal range, and greater voice-use confidence; all girls lost confidence in their voice use over the year.

Conclusions

In this longitudinal study of twenty 13-year-old girls, voice changes in SFo, vocal range, and pitch-break frequency were synchronous with certain weight ranges. Girls with training registered higher maximum phonational frequency and were more confident in their voice use than girls without training.     

Objective Vocal Quality in Children Using Cochlear Implants: A Multiparameter Approach

Objectives

The purpose of this study was to determine the objective vocal quality in 36 prelingually deaf children using cochlear implant (CI) with a mean age of 9 years. An additional purpose was to compare the objective vocal quality of these 36 CI users with 25 age-matched children with prelingual severe hearing loss using conventional hearing aids (HAs) and 25 normal hearing (NH) children.

Study Design

The design for this cross-sectional study was a multigroup posttest-only design.

Methods

The objective vocal quality was measured by means of the dysphonia severity index (DSI). Moreover, perceptual voice assessment using the GRBASI scale was performed.

Results

CI children have a vocal quality by means of the DSI of +1.8, corresponding with a DSI% of 68%, indicating a borderline vocal quality situated 2% above the limit of normality. The voice was perceptually characterized by the presence of a very slight grade of hoarseness, roughness, strained phonation, and higher pitch and intensity levels. No significant objective vocal quality differences were measured between the voices of the CI children, HA users, and NH children.

Conclusions

According to the results, one aspect of the vocal approach in children with CI and using HAs must be focused on the improvement of the strained vocal characteristic and the use of a lower pitch and intensity level.     

Relation between perceived voice register and flow glottogram parameters in males

The perception of modal and falsetto registers was analyzed in a material consisting of a total of 104 vowel sounds sung by 13 choir singers, 52 sung in modal register, and 52 in falsetto register. These vowel sounds were classified by 16 expert listeners in a forced choice test and the number of votes for modal was compared to the voice source parameters: (1) closed quotient (Q(closed)), (2) level difference between the two lowest source spectrum partials (H1-H2), (3) AC amplitude, (4) maximum flow declination rate (MFDR), and (5) normalized amplitude quotient (NAQ, AC amplitude/MFDR(*) fundamental frequency). Tones with a high value of Q(closed) and low values of H1-H2 and of NAQ were typically associated with high number of votes for modal register, and vice versa, Q(closed) showing the strongest correlation. Some singer subjects produced tones that could not be classified as either falsetto or modal register, suggesting that classification of registers is not always feasible.     

The contribution of aryepiglottic constriction to “ringing” voice quality—A videolaryngoscopic study with acoustic analysis

Fiberscopic video laryngoscopy was performed on five professional singers to determine the presence or absence of aryepiglottic narrowing as a function of voice quality. Each sang “Happy Birthday” and parts of the “Star Spangled Banner” in six different voice qualities: speech, falsetto, sob (a low larynx with a vocal tract expanded by relaxing the middle constrictors), twang, belting, and opera. Several features were found to be common among the subjects and related to specific qualities. Aryepiglottic constriction was present in all singers in twang, belting, and opera qualities. Spectrographic analysis related the constriction to the presence of the “singer's formant.” The presence of this type of constrictive behavior will require further research to ascertain the possible benefits to those for whom a louder voice is essential and to understand the relationship of this constrictive maneuver to the natural closure functions of the larynx.     

Investigating the Effects of Caffeine on Phonation

Objective

A core component of vocal hygiene programs is the avoidance of agents that may dry the vocal folds. Clinicians commonly recommend that individuals reduce caffeine intake because of its presumed dehydrating effects on the voice. However, there is little evidence that ingestion of caffeine is detrimental to voice production. The first objective of this study was to evaluate whether caffeine adversely affects voice production. The second objective was to evaluate if caffeine exacerbates the adverse phonatory effects of vocal loading.

Study Design

Prospective, double-blinded, sham-controlled study.

Methods

Sixteen healthy adults participated in two sessions where they consumed caffeine (caffeine concentration = 480 mg) or sham (caffeine concentration = 24 mg) beverages. Voice measures (phonation threshold pressure and perceived phonatory effort) were collected. Subjects then completed a vocal loading challenge and voice measures were obtained again.

Results

There were no significant differences in voice measures between the caffeine and sham conditions. Ingestion of caffeine did not adversely affect voice production (P > 0.05) or exacerbate the detrimental phonatory effects of vocal loading (P > 0.05).

Conclusions

Our findings contribute to emerging knowledge on the effects of caffeine on voice production. Recommendations to completely eliminate caffeine from the diet, as a component of a vocal hygiene program, should be evaluated on an individual basis.     

Comparison of biomechanical modeling of register transitions and voice instabilities with excised larynx experiments

Voice instabilities were studied using excised human larynx experiments and biomechanical modeling. With a controlled elongation of the vocal folds, the experiments showed registers with chest-like and falsetto-like vibrations. Observed instabilities included abrupt jumps between the two registers exhibiting hysteresis, aphonic episodes, subharmonics, and chaos near the register transitions. In order to model these phenomena, a three-mass model was constructed by adding a third mass on top of the simplified two-mass model. Simulation studies showed that the three-mass model can vibrate in both chest-like and falsetto-like patterns. Variation of tension parameters which mimic activities of laryngeal muscles could induce transitions between both registers. For reduced prephonatory areas and damping constants, extended coexistence of chest and falsetto registers was found, in agreement with experimental data. Subharmonics and deterministic chaos were observed close to transitions between the registers. It is concluded that the abrupt changes between chest and falsetto registers can be understood as shifts in dominance of eigenmodes of the vocal folds.     

Multiparametric Analysis of Vocal Fold Vibrations in Healthy and Disordered Voices in High-Speed Imaging

Objectives

The aim of this study was to look for visual subjective and objective parameters of vocal fold dynamics being capable of differentiating healthy from pathologic voices in daily clinical practice applying endoscopic high-speed digital imaging (HSI).

Study Design and Methods

Four hundred ninety-six datasets containing 80 healthy and 416 pathologic subjects (232 functional dysphonia (FD), 13 bilateral, and 171 unilateral vocal fold nerve paralysis) were analyzed retrospectively. Videos at 4000 Hz (256 × 256 pixel) were recorded during sustained phonation. Subjective parameters were visually evaluated and complemented by an analysis of objective parameters. Visual subjective parameters were mucosal wave, glottal closure type, glottal closure insufficiency (GI), asymmetries of the vocal folds, and phonovibrogram (PVG) symmetry. After image segmentation, objective parameters were computed: closed quotient, perturbation measures (PMs) of glottal area, and left-right asymmetry values.

Results

HSI evaluation enabled to distinguish healthy from pathologic voices. For visual subjective parameters, GI, symmetrical behavior, and PVG symmetry exhibited statistical significant differences. For 95% of the data, objective parameters could be computed. Among objective parameters, closed quotient, jitter, shimmer, harmonic-to-noise ratio, and signal-to-noise ratio for the glottal area function differentiated statistically significant normal from pathologic voices. Applying linear discriminant analysis by combining visual subjective and objective parameters, accurate classifications were made for 63.2% of the female and 87.5% of the male group for the three-class problem (healthy, FD, and unilateral vocal fold nerve paralysis).

Conclusion

Actual acoustically applied PMs can be transferred to clinical beneficial HSI analysis. Combining visual subjective and objective basic parameters succeeds in differentiating pathologic from healthy voices. The presented evaluation can easily be included into everyday clinical practice. However, further research is needed to broaden our understanding of the variability within and across healthy and pathologic vocal fold vibrations for diagnosing voice disorders and therapy control.     

Vocal Fold Vibration and Phonation Start in Aspirated, Unaspirated, and Staccato Onset

Objectives/Hypotheses

Singers learn to produce well-controlled tone onsets by accurate synchronization of glottal adduction and buildup of subglottal pressure. Spectrographic analyses have shown that the higher spectrum partials are present also at the vowel onset in classically trained singers’ performances. Such partials are produced by a sharp discontinuity in the waveform of the transglottal airflow, presumably produced by vocal fold collision.

Study Design

After hearing a prompt series of a triad pattern, six singer subjects sang the same triad pattern on the vowel /i/ (1) preceded by an aspirated /p/, (2) preceded by an unaspirated /p/, and (3) without any preceding consonant in staccato.

Methods

Using high-speed imaging we examined the initiation of vocal fold vibration in aspirated and unaspirated productions of the consonant /p/ as well as in the staccato tones.

Results

The number vibrations failing to produce vocal fold collision were significantly higher in the aspirated /p/ than in the unaspirated /p/ and in the staccato tones. High frequency ripple in the audio waveform was significantly delayed in the aspirated /p/.

Conclusions

Initiation of vocal fold collision and the appearance of high-frequency ripple in the vowel /i/ are slightly delayed in aspirated productions of a preceding consonant /p/.     

Construction of a central extension of a Lie group from its class of symplectic cohomology

Bargmann’s group is a central extension of Galilei group motivated by quantum-theoretical considerations. Bargmann’s work suggests that one of the reasons of the failure of naïve attemps to construct actions on quantum wave functions has a cohomologic origin. It is this point, we develop in the context of Lie groups with symplectic actions. Studying the co-adjoint representation of a central extension of a group G$G$, we highlight the link between the extension cocycles and the symplectic cocycles of G$G$. Also, each extension coboundary corresponds to a symplectic coboundary. Finally, we emphasize the condition to be satisfied by the extension cocycle for the class of symplectic cohomology of the extension being null. The method is illustrated by application to Physics.     

Canonical gravity in the parametric manifold picture

Canonical structures in the parametric picture of gravitation in general relativity are investigated. One of the fields, the scalarf, emerges as a secondary entity that interacts with a system consisting of the threemetricg and the connection form. We are employing the (g,) system for developing a canonical approach. While a naïve attempt would appear to founder, we do find an extension of the phase-space of the system which is computationally viable.