Vocal fold strain and vocal pitch in singing: radiographic observations of singers and nonsingers

Características da voz falada de idosas com prática de canto coral

RESUMO Introdução Apesar dos vários estudos relacionados à voz na terceira idade e o canto, ainda são necessárias pesquisas que busquem entender os efeitos dessa prática na voz falada de idosos. Objetivo comparar as características da voz falada de idosas com prática de canto coral às de idosas sem essa vivência. Método fizeram parte deste estudo 75 idosas, sendo 50 com prática de canto coral que compuseram o grupo corista (GC) e 25 sem essa prática (GNC), que foram comparadas. Para caracterização das idosas e levantamento de dados referentes aos hábitos de vida e voz, foi aplicado um questionário. Foram coletadas amostras de fala (vogal sustentada, repetição de frases e um trecho de fala espontânea) em uma sala silenciosa com as idosas sentadas. As vozes foram analisadas por três juízes fonoaudiólogos segundo o protocolo Consensus Auditory–Perceptual Evaluation of Voice (CAPE-V). Os dados foram submetidos à análise descritiva e estatística. Resultados as vozes das idosas do GNC apresentaram aumento significativo nos escores relacionados à alteração do grau geral e presença de rugosidade e tensão. Conclusão A análise das características da voz falada de idosas coristas, quando comparada a daquelas que não realizam essa prática, apontou para melhor qualidade vocal no aspecto geral, em decorrência de menor rugosidade e tensão.

Permeability of canine vocal fold lamina propria

OBJECTIVES/HYPOTHESIS

Determine the permeability of excised canine vocal fold lamina propria.

STUDY DESIGN

Basic science.

METHODS

Vocal folds were excised from canine larynges and mounted within a device to measure the flow of 0.9% saline through the tissue over time. The resultant fluid volume displaced over time was then used in a variation of Darcy's law to calculate the permeability of the tissue. Permeability was found through each anatomical plane of the vocal fold, with five samples per plane. Permeability was also found for lamina propria stretched to 10%, 20%, and 30% of its initial length to determine the effects of tensile strain on permeability, with five samples per level of strain.

RESULTS

Permeability was found to be 1.40 × 10(-13) m(3) s/kg through the sagittal plane, 1.00 × 10(-13) m(3) s/kg through the coronal plane, and 4.02 × 10(-13) m(3) s/kg through the axial plane. It was significantly greater through the axial plane than both the sagittal (P = .025) and coronal (P = .009) planes. Permeability under strain through the sagittal plane was found to be 1.94 × 10(-13) m(3) s/kg under 10% strain, 3.35 × 10(-13) m(3) s/kg under 20% strain, and 4.80 × 10(-13) m(3) s/kg under 30% strain. The permeability significantly increased after 20% strain (P < .05).

CONCLUSIONS

Permeability in canine vocal fold lamina propria was found to be increased along the anterior-posterior axis, following the length of the vocal folds. This may influence fluid distribution within the lamina propria during and after vibration. Similarly, permeability increased after 20% strain was imposed on the lamina propria, and may influence vocal fold dynamics during certain phonation tasks.

LEVEL OF EVIDENCE

NA Laryngoscope, 125:941-945, 2015.

Real-time ultrasonographic assessment of true vocal fold length in professional singers

PURPOSE

To assess changing true vocal fold (TVF) length with ultrasonography.

MATERIALS

Thirty-five professional singers (12 tenors and 23 sopranos) were included in this study. Each subject had a documented TVF length with laryngeal ultrasonography (SonoAce X6 scanner; Samsung Medison, Seoul, Korea) during respiration, phonation, and singing.

RESULTS

The average TVF lengths could be measured in each situation with real-time laryngeal ultrasonography. The mean (standard deviation [SD]) of TVF length was 1.71 cm (0.29) at inspiration, 1.56 cm (0.26) at expiration, 1.70 cm (0.21) at comfort phonation, 2.00 cm (0.22) at the highest tone, and 1.47 cm (0.19) at the lowest tone in tenors. In sopranos, the mean (SD) was 1.35 cm (0.12) at inspiration, 1.17 cm (0.12) at expiration, 1.42 cm (0.12) at comfort phonation, 1.65 cm (0.12) at the highest tone, and 1.14 cm (0.15) at the lowest tone. All variables had significant differences between both sexes (P<0.01). The lengths showed statistically significant differences in each phase (P<0.01). The differences in length between each phase were evaluated as well. When analyzed in each sex, all variables were statistically different except few of them. In both sexes, the highest tone and comfort phonation showed no difference (P=0.081 in tenors and P=0.289 in sopranos). The inspiratory phase and comfort phonation had significant difference only in sopranos (P<0.01) in contrast to tenors (P=0.905).

CONCLUSION

Ultrasonographic measurement of TVF could be used to assess physiological variation of TVF. To reach a high-pitched voice, the professional singers used similar range of TVF length at comfort phonation. TVF length was affected more by inspiration in tenors. In sopranos, TVF at comfort phonation was significantly lengthened than in tenors.

The anisotropic hyperelastic biomechanical response of the vocal ligament and implications for frequency regulation: a case study

One of the primary mechanisms to vary one's vocal frequency is through vocal fold length changes. As stress and deformation are linked to each other, it is hypothesized that the anisotropy in the biomechanical properties of the vocal fold tissue would affect the phonation characteristics. A biomechanical model of vibrational frequency rise during vocal fold elongation is developed which combines an advanced biomechanical characterization protocol of the vocal fold tissue with continuum beam models. Biomechanical response of the tissue is related to a microstructurally informed, anisotropic, nonlinear hyperelastic constitutive model. A microstructural characteristic (the dispersion of collagen) was represented through a statistical orientation function acquired from a second harmonic generation image of the vocal ligament. Continuum models of vibration were constructed based upon Euler-Bernoulli and Timoshenko beam theories, and applied to the study of the vibration of a vocal ligament specimen. From the natural frequency predictions in dependence of elongation, two competing processes in frequency control emerged, i.e., the applied tension raises the frequency while simultaneously shear deformation lowers the frequency. Shear becomes much more substantial at higher modes of vibration and for highly anisotropic tissues. The analysis was developed as a case study based on a human vocal ligament specimen.

Acoustic features for identifying constitutions in traditional Chinese medicine

OBJECTIVES

Constitutions are Traditional Chinese Medicine syndromes that are used to classify symptoms. The present study sought to identify objective acoustic features for eight commonly occurring abnormal constitutions.

METHODS

Speech signals were obtained from 281 subjects through a 1-second vowel sound, /a/, uttered by the subjects. For each constitution, differences in acoustic parameters between the low-score and high-score groups were compared.

RESULTS

Subjects in the high-score groups for Yin-deficiency, Qi-deficiency, Phlegm-wet, Blood-stasis, and Qi-depression showed lower acoustic intensities than subjects in the corresponding low-score groups (all p<0.05). Subjects in the high-score groups of Qi-deficiency and Blood-stasis exhibited higher maximum pitches and higher minimum pitches than subjects in the low-score groups (all p<0.01). The average number of zero-crossings was lower in the high-score groups of Qi-deficiency and Blood-stasis than in the low-score groups for both constitutions (p<0.05). Subjects in the high-score group of special diathesis demonstrated higher low-spectral-energy ratios than subjects in the low-score group (p<0.05), and subjects in the high-score group of Blood-stasis had higher middle spectral energy ratios than subjects in the low-score group (p<0.05). In contrast, the middle spectral energy ratio in the high-score group of special diathesis was lower than in its corresponding low-score group (p<0.05). The high spectral energy ratios were lower in the high-score groups for Yin-deficiency and Blood-stasis (both p<0.05) than in the low-score groups.

CONCLUSIONS

The present study identified acoustic features for constitutions and established objective methods for constitutional diagnosis. These acoustic features can potentially be applied in the expert system of Traditional Chinese Medicine for the diagnosis of constitutions in the general population.

Analysis of male singers laryngeal vertical displacement during the first passaggio and its implications on the vocal folds vibratory pattern

OBJECTIVES

The first voice passaggio in classical western singing is characterized by changes in the vocal tract resonance and configuration around the middle C region (261.62 Hz). Many singers agree that something occurs at the level of the vocal folds to aid the demand for higher frequencies. However, although many singers explore this transitional mechanism, little is known about its precise physiology and association with the vertical displacement of the larynx. The objective of this study is to describe the implications of the vocal tract readjustment and the vocal folds vibration during the passaggio.

METHODS

The study consisted of 11 well-experienced singers performing an ascending scale up to a few notes above middle C while maintaining a consistent vocal tract configuration and finally sustaining the very last note, hence violating the normal passaggio. Subsequently, they reproduced the last sustained note with their traditional configuration of the larynx--western opera singing style. The data were collected with an electroglottography device. A repeated-measures analysis of variance (ANOVA) was applied to analyze the vocal tract length changes, vocal fold contact area (VFCA), and closure quotient before and after the first passaggio. A paired sample t test was implemented to analyze the formants transition.

RESULTS

The results show a significant difference of scores for the formants transition, VFCA, and vocal tract length suggesting that the larynx lowers after the passaggio. This displacement of the larynx is associated with changes on the vocal folds vibratory pattern conjecturably altering from essentially isotonic contraction of the thyroarytenoid muscle to isometric contraction.

The demands of professional opera singing on cranio-cervical posture

Difficulty with singing is a rare but important complication following cervical spine surgery but there is little objective information regarding the cervical and head postural changes taking place during singing. The aim of this study was to identify postural changes in the cranio-cervical region associated with the demands of voice production in professional opera singing. The two Roentgen-cephalograms, one of which are taken whilst performing a specified singing task were taken from 18 professional opera students, 12 females (mean age 20.86 +/- 3.07 years) and six males (18.66 +/- 1.36 years). A paired t test compared mean cranio-cervical postural and pharyngeal/hyoid variables between the two registrations (P = 0.05). The association between the cranio-cervical postural variables and the pharyngeal/hyoid region in each registration position was examined using Spearman's rank correlation coefficient. In singing, the position of the atlas with respect to the true vertical (P < 0.001), the axis (P < 0.001) and the C4 vertebra both with respect to the horizontal (P < 0.001), and the axis with respect to the cranium (P < 0.001), were all significantly different to those at rest. Of the cranio-cervical postural variables in the singing registration, the angles measuring positional change of the atlas and C4 relative to the true horizontal were shown be significantly related to an increased pharyngeal airway space at the C3 level (P < 0.01). An appreciation of the requirement for the cervical spine to undergo postural change during professional opera singing has relevance to the potential impact on voice quality in professional opera singers should they undergo cervical spine surgery.

Laryngeal and respiratory behavior during pitch change in professional singers

The aim of this study was to examine the physiology of pitch change in terms of laryngeal and respiratory mechanisms in professional singers. Nine female professional singers were recruited to participate in the study. Videoendoscopic recordings of the participants producing one-octave ascending and descending scales were used as a basis to apply a ratio measurement of vocal fold length for each note produced on the scale. Simultaneous respiratory data using Respitrace were also collected. Questionnaires (Voice Handicap Index and Vocal Questionnaire) were used to obtain information about psychosocial aspects related to voice use. Two vocal fold lengthening patterns (static and dynamic) were observed with pitch change. Participants exhibiting a static pattern of vocal fold lengthening had fewer years of vocal training, exhibited a more variable use of vital capacity, and also began the singing task at a higher position in their vital capacity. The reverse was true for participants exhibiting a dynamic vocal fold pattern. These preliminary data indicate that the pattern of vocal fold lengthening exhibited by singers may be related to the number of years of training possessed. Furthermore, the data indicate that stability in one subsystem may result in variability in another, as shown by the interaction between the vocal fold and respiratory patterns.

Vocal fold dimensions in professional opera singers as measured by means of laser triangulation

A new laser triangulation technique was used to measure vocal fold length and width in 27 professional opera singers. The singers belonged to different voice register categories: soprano, mezzo, tenor, and bass/baritone. High-speed recordings were made during glissandos from each singer's speaking fundamental frequency (SFF) up to the highest frequency for which it was possible to place the laser spot on the vocal folds. Vocal fold length and width were measured at the singers' SFF and then at two or three times the SFF, and for some singers at four times the SFF. In addition, measurements were also made at C4 (260 Hz) for all singers. The results confirmed that the bass/baritone group had significantly longer vocal folds than the soprano group; also, males have significantly longer vocal folds than females. Measured values for vocal fold width were significantly larger for the bass/baritone group compared with all other groups. A measured strain parameter showed different patterns of vocal fold elasticity with increasing pitch. The results suggest that although vocal fold length and width contribute to a singer's voice register category, there seem to be also other parameters that are essential for this distinction.

Clinical feasibility of the new technique of functional 3D laryngeal CT

CONCLUSIONS

Functional 3D laryngeal CT (F3DLxCT) is an informative tool for visualizing the active changes in length, tension and mass of the vocal folds for pitch control. Furthermore, volume defects and level differences of paralyzed vocal folds are easily detectable with this new technique.

OBJECTIVE

To evaluate the clinical feasibility of F3DLxCT images, which can provide clear coronal images of the vocal fold in each anteroposterior direction during phonation and in the resting state.

MATERIAL AND METHODS

FLxCT images were reconstructed to three dimensions to visualize laryngeal motion. FLxCT was performed in four normal controls and in four patients with unilateral vocal fold paralysis in the resting state and during phonation with three vowel sounds of different pitch. 3D images were reconstructed with segmentation and a surface-rendering algorithm on a PC, using the DICOM file of axial images.

RESULTS

The dynamic vocal fold 3D image during phonation could visualize that the thickness and volume were decreased in relatively to the pitch increase. Typical subglottic shoulder-like image formation and ventricular widening were noted with the high-pitch tone.

Pitch-synchronous changes in the anterior cricothyroid space during singing

Pitch-synchronous changes in the anterior cricothyroid (CT) space were registered with ultrasonography (USG) for ten healthy subjects (5 males, 5 females) during the production of musical fifths throughout the whole voice range. One of the males and one of the females were trained amateur singers, the other subjects were choir singers. The average decrease in CT space per a musical fifth was 1.3-2.4 mm for the males and 1.0-1.8 mm for the females; the average decrease was smaller in the middle of the pitch range for both genders. The results suggest that (1) USG can be used for detection of pitch-synchronous changes in the CT space; (2) these changes are dependent on pitch range; and (3) more trained singers tend to have somewhat smaller changes than less trained subjects at certain frequencies. The results seem to indicate that F0 control mechanism varies according to pitch range and register, and possibly according to individual structure and vocal technique related differences.

The external frame function in the control of pitch, register, and singing mode: radiographic observations of a female singer

This study investigates pitch control, register, and singing mode related movements of the laryngo-pharyngeal structures by radiographic methods. One trained female singer served as the subject. The results show that singing voice production involves complex movements in the laryngeal structures. Pitch related increase in the thyro-arytenoid distance (vocal fold length) is nonlinear, slowing down as pitch rises. Similar observations have been made earlier. At the highest pitches, a shortening of the distance can be seen, suggesting the use of alternative pitch control mechanisms. The various observations made support the existence of three registers in this trained female singing voice. Open and covered modes of singing seemed to be distinguishable on the basis of different amounts of inner and outer forces acting on the larynx. Therefore, caution must be exercised when generalizing from the results.