Using Electroglottographic Real-Time Feedback to Control Posterior Glottal Adduction during Phonation

Biofeedback electromiográfico y electroglotográfico aplicado a la terapia vocal: una revisión sistemática

La electromiografía y electroglotografía son técnicas de exploración que, combinadas con el biofeedback, permiten en el emisor ajustes musculares para la mejora de la función fonatoria. Nos proponemos, pues, determinar los efectos del biofeedback electromiográfico para aumentar o disminuir el tono en los músculos que intervienen de manera indirecta o directa en la producción de la voz, identificar los efectos del biofeedback electroglográfico para producir cambios en el patrón vibratorio de los pliegues vocales y, finalmente, determinar la frecuencia del biofeedback en el tratamiento vocal, a partir de una revisión sistemática de los trabajos publicados desde el año 2000 en revistas logopédicas y laringológicas. El análisis de los estudios obtenidos en el proceso de documentación sugiere que el uso del biofeedback electromiográfico y electroglotográfico puede producir cambios perdurables en el tiempo sobre el patrón vibratorio de los pliegues vocales y en la actividad muscular de la producción vocal, de manera que podría ser un instrumento útil añadido a la intervención vocal basadaen la evidencia. Los datos relativos a la frecuencia de uso necesaria de este instrumento, sin embargo, no parecen concluyentes.

Nebulized Saline Solution: A Multidimensional Voice Analysis

PURPOSE

To verify the effect of nebulization on the voice of dysphonic and non-dysphonic individuals on acoustic, perceptual-auditory, aerodynamic, electroglottographic, laryngeal parameters and on the self-perception of vocal discomfort.

MATERIALS AND METHODS

All the research subjects were submitted to vocal evaluation, laryngeal and voice self-perception. Then, the participants remained in vocal rest for a period of 10 minutes and the analysis mentioned above were again performed. After this first stage, the participants were submitted to the nebulization for a period of 10 minutes and the all analysis above were again performed. Descriptive analysis of the variables was carried. In the comparison of the pre- and post-nebulization groups, the Paired T-Student Test was used for variables with non-dysphonic distribution and the Wilcoxon Test for variables with asymmetric distribution. When categorical variables were evaluated (perceptual-auditory evaluation and laryngeal assessment), the Pearson's Chi-square test was used. In all analysis, a significance level of 5% was considered. The intra-rater agreement in the auditory-perceptual and perceptual-visual assessment was assessed using the AC1 statistic, using the R program. For this purpose, 20% of the voice samples and laryngeal images were replicated blindly and interpreted by the evaluators at the time evaluations.

RESULTS

The results of this research show that non-dysphonic individuals have more positive vocal and laryngeal effects after nebulization than dysphonic ones. It is also observed that the EGG measurement was the most sensitive to the effect of nebulization, with an increase in the Closed quotient (CQ) in all groups evaluated. Regarding acoustic measurements, it is noted that the effect of nebulization in men is more evident than in women. After nebulization, there was an increase in fundamental frequency in the group of non-dysphonic women and dysphonic and non-dysphonic men. A decrease in the amplitude perturbation quotient values is observed in all groups, besides a reduction in the pitch perturbation quotient values after nebulization in non-dysphonic men groups. There was improves aerodynamic efficiency in groups of dysphonic and non-dysphonic men and in the self-perception of vocal discomfort in all groups studied after the hydration procedure. The results of this study demonstrate a significant improvement in the mucosal wave after nebulization in the groups of women and men who are not dysphonic.

CONCLUSION

The nebulization procedure with saline solution improves acoustic measurements, the electroglottographic closed quotient and vocal self-perception of dysphonic and non-dysphonic women and men. Nebulization increases the mucosal wave of the vocal folds in non-dysphonic women and men and improves the aerodynamic efficiency of men.

Análise das medidas eletroglotográficas da voz: padrões de normalidade para cantores por meio do programa CSL da Kay Pentax®

RESUMO Objetivo: Analisar as medidas de frequência fundamental, jitter eletroglotográfico, quociente de contato e periodicidade das ondas eletroglotográficas da voz de cantores em registro modal. Método: Estudo observacional de corte transversal que selecionou indivíduos de escolas de canto da região central do município de Belo Horizonte-MG. A amostra foi não probabilística, por conveniência, composta por 60 indivíduos cantores com faixa etária entre 18 e 55 anos, sendo 30 homens e 30 mulheres. Para a coleta do registro eletroglotográfico, foi utilizado o programa CSL da Kay Pentax™, model 6103, módulo Electroglottography. Os participantes foram posicionados sentados e, após a higienização da pele do pescoço com álcool 70 %, dois eletrodos foram colocados nas alas da cartilagem tireóidea no nível das pregas vocais. Posteriormente, os participantes foram orientados a emitir a vogal /a/ sustentada de forma habitual. Foram analisadas as medidas de frequência fundamental (f0), quociente de contato (QC), jitter eletroglotográfico e periodicidade da onda eletroglotográfica. Os dados foram analisados estatisticamente utilizando o Minitab 17. Resultados: Os parâmetros analisados foram estatisticamente significantes. A frequência fundamental (f0) foi maior nas mulheres (226,91 Hz) quando comparada com a dos homens (166,54 Hz). As medidas de quociente de contato e de periodicidade também foram maiores nas mulheres (40,46 % e 15,51 %, respectivamente) se comparadas às dos homens (27,45 % e 7,82, respectivamente). O parâmetro de jitter foi maior nos homens, quando comparado ao das mulheres. Conclusão: Os valores de frequência fundamental (f0), quociente de contato (QC) e periodicidade da onda foram maiores nas mulheres. O valor de jitter foi maior nos homens.

Comparison of electroglottographic variability index in euphonic and pathological voice

In a recent study we introduced a new approach for analysis of the electroglottographic (ECG) signal. This method is based on the evaluation of variation of the EGG signal and its first derivative, through new software developed by the Pisan phoniatric school. This software is designed to extract quantitative indices related to the contacting and decontacting phases of the vocal folds during phonation. The software allows us to study the combined variability of vibration amplitude and velocity (i.e. the first derivative of the EGG signal). Pathological voices show a much more variable EGG signal compared to normal voices, since cordal vibration is made irregular due to the presence of glottis plane pathologies. With the aim of demonstrating the differences between normal and pathological voices relevant to combined vibration amplitude and velocity variability, we have introduced a new quantitative parameter named “variability index, VI”. We studied 95 subjects (35 normal and 60 with pathological voice); among pathologic subjects, 15 showed functional dysphonia and 45 showed organic dysphonia. Subjects affected by organic dysphonia presented: 15 bilateral vocal nodules, 15 unilateral polyps and 15 unilateral cysts. All subjects were studied with videolaryngostroboscopy; electro-acoustic parameters of the voice were analysed with the KayPENTAX CSL (Model 4500) system. The EGG signal was recorded using KAY Model 6103 connected to the CSL system. The new software for the analysis of the EGG signal allows us to obtain not only a VI total value relevant to variability during all the recording, but also partial VI values relevant to the different glottis cycle phases. In fact, plotting the amplitude variation and its first derivative on a Lissajous graph, it is possible to divide the whole glottis cycle into four phases (each represented by four quadrants on the graph): the initial vocal folds contacting activity (VI-Q1), the last phase of vocal folds contacting (VI-Q2), the first phase of vocal folds decontacting (VI-Q3) and the last phase, up to the complete decontacting of vocal folds (VI-Q4). For each quadrant, it is also possible to work out the percent variability index. By comparing the variability indices in the normal and pathological groups, we obtained the following results: the total VI was significantly higher in the pathological subjects (0.25 vs 0.18; p = 0.01); the absolute value of VI was higher in pathological subjects, although the difference was not significant (VI-Q2, 0.041 vs 0.029; VI-Q3, 0.065 vs 0.058; VI-Q4, 0.054 vs 0.052). The percent variability in the Q2 quadrant (VI-Q2%) was significantly higher in pathological subjects compared to normal subjects (0.22 vs 0.16) (p = 0.01). The results of this study confirm that our new software for analysis of EGG signal can distinguish normal voice from pathological voice based on the new quantitative parameter VI. Moreover, this study emphasises that the final contact phase of vocal folds is the most representative of the difference between the normal and pathological voice and shows a wider variability in terms of amplitude and vibration velocity. Further studies on larger groups of subjects will be required to confirm these results and assess differences in the EGG signal among the various vocal fold pathologies.

Glottal Adduction and Subglottal Pressure in Singing

Previous research suggests that independent variation of vocal loudness and glottal configuration (type and degree of vocal fold adduction) does not occur in untrained speech production. This study investigated whether these factors can be varied independently in trained singing and how subglottal pressure is related to average glottal airflow, voice source properties, and sound level under these conditions. A classically trained baritone produced sustained phonations on the endoscopic vowel [i:] at pitch D4 (approximately 294 Hz), exclusively varying either (a) vocal register; (b) phonation type (from "breathy" to "pressed" via cartilaginous adduction); or (c) vocal loudness, while keeping the others constant. Phonation was documented by simultaneous recording of videokymographic, electroglottographic, airflow and voice source data, and by percutaneous measurement of relative subglottal pressure. Register shifts were clearly marked in the electroglottographic wavegram display. Compared with chest register, falsetto was produced with greater pulse amplitude of the glottal flow, H1-H2, mean airflow, and with lower maximum flow declination rate (MFDR), subglottal pressure, and sound pressure. Shifts of phonation type (breathy/flow/neutral/pressed) induced comparable systematic changes. Increase of vocal loudness resulted in increased subglottal pressure, average flow, sound pressure, MFDR, glottal flow pulse amplitude, and H1-H2. When changing either vocal register or phonation type, subglottal pressure and mean airflow showed an inverse relationship, that is, variation of glottal flow resistance. The direct relation between subglottal pressure and airflow when varying only vocal loudness demonstrated independent control of vocal loudness and glottal configuration. Achieving such independent control of phonatory control parameters would be an important target in vocal pedagogy and in voice therapy.

Influence of F0 and Sequence Length of Audio and Electroglottographic Signals on Perturbation Measures for Voice Assessment

OBJECTIVE

Within the functional assessment of voice disorders, an objective analysis of measured parameters from audio, electroglottographic (EGG), or visual signals is desired. In a typical clinical situation, reliable objective analysis is not always possible due to missing standardization and unknown stability of the clinical parameters. The aim of this study was to investigate the robustness/stability of measured clinical parameters of the audio and EGG signals in a typical clinical setting to ensure a reliable objective analysis. In particular, the influence of F0 and of the sequence length on several definitions of jitter and shimmer will be analyzed.

PATIENTS AND METHODS

Seventy-four young healthy women produced a sustained vowel /a/ and an upward triad with abrupt changeovers. Different sequence lengths (100, 150, 500, and 1000 ms) of sustained phonation and triads (100 and 150 ms) were extracted from the audio and EGG signals. In total, six variations of jitter and four variations of shimmer parameters were analyzed.

RESULTS

Jitter%, Jitter11p, and JitterPPQ of the audio signal as well as Jittermean, Shimmer, and Shimmer11p of the EGG signal are unaffected by both sequence length and F0.

CONCLUSIONS

Influence of F0 and sequence length on several perturbation measures of the audio and EGG signals was identified. For an objective clinical voice assessment, unaffected definitions of jitter and shimmer should be preferred and applied to enable comparability between different recordings, examinations, and studies.

Avaliação eletroglotográfica de mulheres disfônicas com lesão de massa

OBJETIVO: comparar os resultados da avaliação eletroglotográfica entre mulheres adultas com laudo otorrinolaringológico de nódulos vocais e presença de fenda glótica com mulheres sem alterações laríngeas. MÉTODO: trata-se de 20 mulheres, sendo 10 com exame otorrinolaringológico de nódulo vocal, associado à fenda glótica, e 10 com vozes avaliadas na análise perceptivo-auditiva como neutras e avaliação otorrinolaringológica sem alteração laríngea. A faixa etária variou de 27 a 55 anos, com média de 37,60 e 36,00 para grupo estudo e controle, respectivamente. O material de voz foi a emissão habitual da vogal sustentada /a/. Foram extraídas as medidas de quociente de contato, frequência fundamental, jitter, bem como a classificação e interpretação dos tipos de ondas e presença do joelho eletroglotográfico. A análise estatística foi realizada pelo teste Exato de Fisher e T de Student. RESULTADOS: todos os traçados foram classificados como tipo II (100%). Não foi observada diferença na presença ou ausência de joelho entre grupos. A média do quociente de contato foi de 42,52 e 45,56 para grupo estudo e controle, respectivamente. Apesar do menor valor para o grupo estudado, não houve diferença significante entre grupos. Houve relação estatisticamente significante entre grupos no que se refere à frequência fundamental e jitter. A média da frequência fundamental foi 193,18 e 211,69 e o valor médio de jitter foi 1,21 e 2,9 para o grupo estudo e controle, respectivamente. CONCLUSÃO: mulheres com lesão de massa nas pregas vocais apresentam maiores valores de jitter e menores valores para frequência fundamental eletroglotográfica.

Vocal tract configurations in male alto register functions

PURPOSE

Professional male altos (countertenors) mostly use a register function, which is considered to be derived from falsetto. However, the sound produced differs in professional altos compared with the modal register or falsetto of untrained voices. The aim of this study was to analyze differences of the vocal tract shapes in male alto register functions.

MATERIAL AND METHODS

Dynamic real-time magnetic resonance imaging of eight frames per second was used to analyze the vocal tract profile in seven professional male altos who sang on the vowel /a/, an ascending and descending scale from G3 (196 Hz) to E4 (330 Hz). The scale included their register transition from modal register to stage (counter) falsetto and naïve falsetto.

RESULTS

Register transitions from modal register to stage falsetto were associated with increased lip opening, jaw retraction, elevation and back positioning of the tongue, pharynx narrowing, uvula elevation, drop of larynx height, and tilting of the larynx. Differences between stage and naïve falsetto were found mostly with regard to lip opening and pharynx width.

CONCLUSIONS

The differences between the vocal tract configurations might have an impact on the acoustic characteristics observed in professional male alto register functions.

Electroglottographic wavegrams: a technique for visualizing vocal fold dynamics noninvasively

A method for analyzing and displaying electroglottographic (EGG) signals (and their first derivative, DEGG) is introduced: the electroglottographic wavegram ("wavegram" hereafter). To construct a wavegram, the time-varying fundamental frequency is measured and consecutive individual glottal cycles are identified. Each cycle is locally normalized in duration and amplitude, the signal values are encoded by color intensity and the cycles are concatenated to display the entire voice sample in a single image, similar as in sound spectrography. The wavegram provides an intuitive means for quickly assessing vocal fold contact phenomena and their variation over time. Variations in vocal fold contact appear here as a sequence of events rather than single phenomena, taking place over a certain period of time, and changing with pitch, loudness and register. Multiple DEGG peaks are revealed in wavegrams to behave systematically, indicating subtle changes of vocal fold oscillatory regime. As such, EGG wavegrams promise to reveal more information on vocal fold contacting and de-contacting events than previous methods.