Glottal Adduction Research Articles

On the acoustic effects of the supraglottic structures in excised larynges

The acoustic effects of the supraglottic laryngeal structures (SGSs), including the false vocal folds (FVFs) laryngeal ventricle, and the epiglottis were investigated in an excised canine larynx model with and without these anatomical structures. The purpose of this study was to better understand the acoustic contributions of these structures to phonation. Canine larynges were prepared and mounted over a 3/4 in. tube, which supplied pressurized, heated, and humidified air. Glottal adduction was accomplished by rotating the arytenoids with a suture passed behind the vocal folds to simulate the lateral cricoarytenoid muscle action. The SGSs were kept intact in the first part of the experiment and were removed in the second part. Results indicated that when the FVFs vibrated, a low frequency component was observed in the spectral data. The excised larynx with a SGS had a limited range of frequency with subglottal pressure, while the larynx without a SGS had a larger frequency range. The excised canine larynx with a SGS oscillated with a higher phonation threshold pressure and significantly louder.

Effects of supraglottic compressions on the aerodynamics and acoustics of excised canine larynges

The purpose of this study was to examine the aerodynamic and acoustic effects due to supraglottic compressions, which may be seen in some dysphonic patients. Canine larynges were prepared and mounted and vocal fold oscillations were generated and controlled by the flow of air through the glottis. Glottal adduction was accomplished by rotating the arytenoids with a suture passed behind the vocal folds to simulate lateral cricoarytenoid muscle action. Supraglottic medial and anterior-posterior compressions were accomplished by manual squeezing at the arytenoid level and alternating between the rest and compressed conditions. The raw data, including EGG, subglottal pressure, flowrate, and microphone signals, were recorded on a DAT tape and later digitized and processed with Matlab. A video image of the superior aspect of the larynx was recorded using a stroboscopic light during the whole experiment. Results indicated that the excised larynges oscillated better and easier without the false vocal folds, but generated louder sound with false vocal folds. Medial compression always resulted in increased subglottal pressure, decreased flow rate and most often increased the sound intensity, but decreased EGG closed quotient. Both of these compressions had negative effects on the amplitude of EGG signal, suggesting disruption of vocal fold contact.

Articulatory gestures are individually selected in production

Most models of speech planning and production incorporate a selection mechanism, whereby units are activated in parallel and chosen for execution sequentially. The lowest level units which can be selected are assumed to be segments, i.e. consonants and vowels. The features or articulatory gestures affiliated with segments are presumed to be automatically selected as a consequence of segmental selection. An alternative possibility is that articulatory gestures themselves are subject to a selection process; this predicts that there can be circumstances in which gestures affiliated with the same segment fail to co-occur. We conducted a stop-signal task in which subjects produced /pa/- or /ka/-initial monosyllables and disyllables in response to a go-signal; on 50% of trials subjects halted production as quickly as possible when given a stop-signal within ±300ms of the go-signal. Articulatory kinematics were recorded using a speech magnetometer. We found that vowel-affiliated gestures of glottal adduction, tongue body lowering, and bilabial opening did not necessarily co-occur in the context of halting speech. This finding indicates that gestures are selected individually, rather than as an automatic consequence of segmental selection.

Measures of Spectral Slope Using an Excised Larynx Model

Spectral measures of the glottal source were investigated using an excised canine larynx (CL) model for various aerodynamic and phonatory conditions. These measures included spectral harmonic difference H1-H2 and spectral slope that are highly correlated with voice quality but not reported in a systematic manner using an excised larynx model. It was hypothesized that the acoustic spectra of the glottal source were significantly influenced by the subglottal pressure, glottal adduction, and vocal fold elongation, as well as the resulting vibration pattern. CLs were prepared, mounted on the bench with and without false vocal folds, and made to oscillate with a flow of heated and humidified air. Major control parameters were subglottal pressure, adduction, and elongation. Electroglottograph, subglottal pressure, flow rate, and audio signals were analyzed using custom software. Results suggest that an increase in subglottal pressure and glottal adduction may change the energy balance between harmonics by increasing the spectral energy of the first few harmonics in an unpredictable manner. It is suggested that changes in the dynamics of vocal fold motion may be responsible for different spectral patterns. The finding that the spectral harmonics do not conform to previous findings was demonstrated through various cases. Results of this study may shed light on phonatory spectral control when the larynx is part of a complete vocal tract system.

Subglottal pressure and fundamental frequency control in contact calls of juvenile Alligator mississippiensis

SUMMARYVocalization is rare among non-avian reptiles, with the exception of the crocodilians, the sister taxon of birds. Crocodilians have a complex vocal repertoire. Their vocal and respiratory system is not well understood but appears to consist of a combination of features that are also found in the extremely vocal avian and mammalian taxa. Anatomical studies suggest that the alligator larynx is able to abduct and adduct the vocal folds, but not to elongate or shorten them, and is therefore lacking a key regulator of frequency, yet alligators can modulate fundamental frequency remarkably well. We investigated the morphological and physiological features of sound production in alligators. Vocal fold length scales isometrically across a wide range of alligator body sizes. The relationship between fundamental frequency and subglottal pressure is significant in some individuals at some isolated points, such as call onset and position of maximum fundamental frequency. The relationship is not consistent over large segments of the call. Fundamental frequency can change faster than expected by pressure changes alone, suggesting an active motor pattern controls frequency and is intrinsic to the larynx. We utilized a two-mass vocal fold model to test whether abduction and adduction could generate this motor pattern. The fine-tuned interplay between subglottal pressure and glottal adduction can achieve frequency modulations much larger than those resulting from subglottal pressure variations alone and of similar magnitude, as observed in alligator calls. We conclude that the alligator larynx represents a sound source with only two control parameters (subglottal pressure and vocal fold adduction) in contrast to the mammalian larynx in which three parameters can be altered to modulate frequency (subglottal pressure, vocal fold adduction and length/tension).

Pregnancy and the Singing Voice: Reports From a Case Study

Significant changes in body tissues occur during pregnancy; however, literature concerning the effects of pregnancy on the voice is sparse, especially concerning the professional classically trained voice. Hormonal variations and associated bodily changes during pregnancy affect phonatory conditions, such as vocal fold motility and glottal adduction. Longitudinal case study with a semiprofessional classically trained singer. Audio, electrolaryngograph, oral pressure, and air flow signals were recorded once a week during the last 12 weeks of pregnancy, 48 hours after birth and during the following consecutive 11 weeks. Vocal tasks included diminuendo sequences of the syllable /pae/ sung at various pitches, and performing a Lied. Phonation threshold pressures (PTPs) and collision threshold pressures (CTPs), normalized amplitude quotient (NAQ), alpha ratio, and the dominance of the voice source fundamental were determined. Concentrations of sex female steroid hormones were measured on three occasions. A listening test of timbral brightness and vocal fatigue was carried out. Results demonstrated significantly elevated concentrations of estrogen and progesterone during pregnancy, which were considerably reduced after birth. During pregnancy, CTPs and PTPs were high; and NAQ, alpha ratio, and dominance of the voice source fundamental suggested elevated glottal adduction. In addition, a perceptible decrease of vocal brightness was noted. The elevated CTPs and PTPs during pregnancy suggest reduced vocal fold motility and increased glottal adduction. These changes are compatible with expected effects of elevated concentrations of estrogen and progesterone on tissue viscosity and water retention.

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

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. 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. 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. 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/. 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/.

Definition and Implications of Novel Pharyngo-Glottal Reflex in Human Infants Using Concurrent Manometry Ultrasonography

Glottal relationships during swallowing dominate the etiology of dysphagia. We investigated the pharyngo-glottal relationships during basal and adaptive swallowing. Temporal changes in glottal closure kinetics (frequency, response latency, and duration) with spontaneous and adaptive pharyngeal swallows were defined in 12 infants using concurrent pharyngoesophageal manometry and ultrasonography of the glottis. Frequency, response latency, and duration of glottal closure with spontaneous swallows (n=53) were 100%, 0.27+/-0.1 s, and 1+/-0.22 s, respectively. The glottis adducted earlier (P<0.0001 vs. upper esophageal sphincter relaxation) within the same respiratory phase as swallow (P=0.03). With pharyngeal provocations (n=41), glottal adduction (pharyngo-glottal closure reflex (PGCR)) was noted first and then again with pharyngeal reflexive swallow (PRS). The frequency, response latency, and duration of glottal closure with PGCR were 100%, 0.56+/-0.13 s, and 0.52+/-0.1 s, respectively. Response latency to PRS was 3.24+/-0.33 s; the glottis adducted 97% within 0.36+/-0.08 s in the same respiratory phase (P=0.03), and remained adducted for 3.08+/-0.71 s. Glottal adduction was the quickest with spontaneous swallow (P=0.04 vs. PGCR), and the duration was the longest during PRS (P<0.005 vs. PGCR or spontaneous swallow). Glottal adduction during basal or adaptive swallowing reflexes occurs in either respiratory phase, thus ensuring airway protection against pre-deglutitive or deglutitive aspiration. The independent existence and magnitude (duration of adduction) of PGCR suggests a hypervigilant state of the glottis in preventing aspiration during swallowing or during high gastroesophageal reflux events. Investigation of pharyngeal-glottal relationships with the use of noninvasive methods may be more acceptable across the age spectrum.

Função fonatória em pacientes com doença de Parkinson: uso de instrumento de sopro

OBJETIVO: verificar o efeito da terapia com instrumento de sopro na função fonatória de pacientes com doença de Parkinson, com enfoque nas avaliações laríngeas, acústicas, respiratórias e de intensidade vocal. MÉTODOS: esta pesquisa é um estudo de caso coletivo e prospectivo. Dois sujeitos foram submetidos a exame videolaringoscópico, avaliação da função respiratória, gravação de amostras da voz, medição da intensidade vocal e terapia. Para a análise acústica foi utilizado o programa Multidimensional Voice Program advanced. A análise dos dados foi ponderada, uma vez que a pesquisa é um estudo de caso coletivo. RESULTADOS: os resultados mostraram que as modificações respiratórias, acústicas e de intensidade vocal foram similares e positivas nos dois sujeitos estudados. CONCLUSÃO: a terapia realizada com o instrumento de sopro pode proporcionar maior eficiência na adução glótica, e melhor movimentação e controle respiratório, propiciando o uso mais efetivo do ar para fonação, com melhora da qualidade vocal, expressa pela redução das medidas de ruído, maior estabilidade fonatória e aumento da intensidade vocal.

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

The goal of this pilot study was to determine whether the ability to change the degree of posterior glottal adduction (PGA) during phonation can be acquired more easily with the aid of electroglottographic (EGG) real-time feedback. The subject was a 37-year-old untrained female with habitually breathy voice. Before the experiment, she participated in one voice coaching session where exercises for increasing PGA were explained and executed. During the experiment, phonation has been monitored simultaneously with videostroboscopy, electroglottography, and audio recording. While phonating, the subject saw amplitude and period normalized EGG waveform representing one glottal cycle consecutively changing over time. The assignment was to increase the width of the EGG waveform during phonation. Laryngeal imaging revealed a posterior glottal chink during habitual phonation. The subject could only introduce intentional changes into the EGG waveform after its relevance had been explained, and after recapitulation of the exercises of the voice coaching session: An increase of the EGG waveform width coincided with the increase of high-frequency partials and an increase of PGA. For pitches B3 and B4, full glottal closure could be achieved. At G5, a reduction of the posterior glottal chink occurred. The findings of this study suggest that the skill to control the degree of PGA can be acquired, and that EGG real-time feedback can be a crucial element in optimizing the process of skill acquisition, but only if (1) the context and nature of the feedback is explained and (2) proper instructions are provided. The EGG contact quotient might not be sensitive to changes of PGA in falsetto phonation.

Effects of a Semioccluded Vocal Tract on Laryngeal Muscle Activity and Glottal Adduction in a Single Female Subject

Voice training exploits semiocclusives, which increase vocal tract interaction with the source. Modeling results suggest that vocal economy (maximum flow declination rate divided by maximum area declination rate, MADR) is improved by matching the glottal and vocal tract impedances. Changes in MADR may be correlated with thyroarytenoid (TA) muscle activity. Here the effects of impedance matching are studied for laryngeal muscle activity and glottal resistance. One female repeated [pa:p:a] before and immediately after (a) phonation into different-sized tubes and (b) voiced bilabial fricative [β:]. To allow estimation of subglottic pressure from the oral pressure, [p] was inserted also in the repetitions of the semiocclusions. Airflow was registered using a flow mask. EMG was registered from TA, cricothyroid (CT) and lateral cricoarytenoid (LCA) muscles. Phonation was simulated using a 7 × 5 × 5 point-mass model of the vocal folds, allowing inputs of simulated laryngeal muscle activation. The variables were TA, CT and LCA activities. Increased vocal tract impedance caused the subject to raise TA activity compared to CT and LCA activities. Computer simulation showed that higher glottal economy and efficiency (oral radiated power divided by aerodynamic power) were obtained with a higher TA/CT ratio when LCA activity was tuned for ideal adduction.

Glottal Airflow Resistance in Excised Pig, Sheep, and Cow Larynges

This study was to investigate glottal flow resistance in excised pig, sheep, and cow larynges during phonation at different oscillation ranges and to examine the relation of the glottal flow resistance to the laryngeal geometry and vocal fold vibration. Several pig, sheep, and cow larynges were prepared, mounted on an excised larynx bench, and set into oscillation with pressurized, heated, and humidified air. Glottal adduction was controlled by either using two-pronged probes to press the arytenoids together, or by passing a suture to simulate the lateral cricoarytenoid muscle action. Each excised larynx was subjected to a series of pressure-flow experiments, with adduction and flow rate as independent variables. The subglottal pressure, fundamental frequency, and glottal flow resistance were treated as dependent variables. The subglottal pressure, electroglottograph (EGG), and flow rate signals were recorded during each experiment. Glottal flow resistance was calculated from the pressure and flow signals, whereas the EGG signal was used to extract fundamental frequency. Preliminary data indicated a nonlinear behavior in the pressure-flow relations of these larynges with increasing glottal resistance due to increases in adduction. The average glottal flow resistance was 35.3+/-14.8 cmH(2)O/(L/s) for the pig, 30.8+/-17.5 cmH(2)O/(L/s) for the sheep, and 26.9+/-14.9 cmH(2)O/(L/s) for the cow.

On pressure-frequency relations in the excised larynx

The purpose of this study was to find relationships between subglottal pressure (P(s)) and fundamental frequency (F(0)) of phonation in excised larynx models. This included also the relation between F(0) and its rate of change with pressure (dFdP). Canine larynges were prepared and mounted over a tapered tube that supplied pressurized, heated, and humidified air. Glottal adduction was accomplished either by using two-pronged probes to press the arytenoids together or by passing a suture to simulate lateral cricoarytenoid muscle activation. The pressure-frequency relation was obtained through a series of pressure-flow sweep experiments that were conducted for eight excised canine larynges. It was found that, at set adduction and elongation levels, the pressure-frequency relation is nonlinear, and is highly influenced by the adduction and elongation. The results indicated that for the lower phonation mode, the average rate of change of frequency with pressure was 2.9+/-0.7 Hzcm H(2)O, and for the higher mode was 5.3+/-0.5 Hzcm H(2)O for adduction changes and 8.2+/-4.4 Hzcm H(2)O for elongation changes. The results suggest that during speech and singing, the dFdP relationships are taken into account.

Aerodynamic and Acoustic Effects of False Vocal Folds and Epiglottis in Excised Larynx Models

The purpose of this study was to examine the aerodynamic and acoustic effects of the false vocal folds and the epiglottis on excised larynx phonation. Several canine larynges were prepared and mounted over a tapered tube that supplied pressurized, heated, and humidified air. Glottal adduction was accomplished either by using two-pronged probes to press the arytenoids together or by passing a suture to simulate lateral cricoarytenoid muscle activation. First, the excised larynx with false vocal folds and epiglottis intact was subjected to a series of pressure-flow experiments with longitudinal tension and adduction as major control parameters. Then, the epiglottis and finally the false vocal folds were removed and the experiment was repeated. The subglottal pressure and the electroglottographic, flow rate, audio, and sound pressure signals were recorded during each experiment. Glottal flow resistance was calculated from the pressure and flow signals. The electroglottographic signal was used to extract the fundamental frequency. It was found that the false vocal folds and the epiglottis offer a positive contribution to the glottal resistance and sound intensity of the larynx. Also, vocal fold elongation and glottal medial compression caused an increase in glottal resistance. The pressure-flow relationships were approximately linear regardless of the structure. The addition of the supraglottic laryngeal structures has a significant impact on both aerodynamic and acoustic characteristics of excised larynges.

Can vocal economy in phonation be increased with an artificially lengthened vocal tract? A computer modeling study

Voiced obstruents and phonation into tubes are widely used as vocal exercises. They increase the inertive reactance of the vocal tract in the 200–1000 Hz range and thereby reinforce vocal fold vibration. But the effect is strong only when the epilarynx tube is also narrowed. The present study focused on the effects of a ‘resonance tube’ (27 cm in length, 0.5 cm2 cross-sectional area, hard walls) on vocal tract reactance and the accompanying economy of voice production (defined as maximum flow declination rate (MFDR), divided by maximum area declination rate (MADR)). The vowel /u/ and phonation into the tube were simulated with a computer model. Three values were given to the cross-sectional area of the epilarynx tube (0.2 cm2, 0.5 cm2, and 1.6 cm2), which is at the opposite end of the vocal tract from the artificial ‘resonance tube’. The degree of glottal adduction was varied in order to find the economy maximum for each epilarynx tube setting.Results showed that the ‘resonance tube’ lowered F1 from 300 Hz to 150 Hz and doubled the vocal tract inertive reactance at F0=100 Hz. The largest economy with the ‘resonance tube’ was obtained when the epilarynx tube was narrowed (relative to the rest of the vocal tract) and sufficiently tight adduction was used. Most importantly, the intraoral acoustic pressure (calculated at 0.8 cm behind the lips) was tripled with the tube. The results suggest that by optimizing the vibratory sensations in the face that are attributed to increased intraoral acoustic pressure, phonation into a tube may assist a trainee in finding an optimal glottal and epilaryngeal setting for the greatest vocal economy.

Acoustic and aerodynamic effects of false folds and epiglottis

Excised larynx research usually excludes the false folds in an effort to reveal the true vocal folds. The purpose of this study was to examine the aerodynamic and acoustic effects of the false folds and epiglottis on excised larynx phonation. Canine larynges were mounted over a tapered tube on the excised larynx bench that supplied pressurized, heated, and humidified air. Glottal adduction was accomplished by passing sutures that simulated lateral cricoarytenoid muscle activation. First, the excised larynx with intact false folds and epiglottis was subjected to a series of pressure-flow experiments with tension and adduction as major control parameters. Then, the epiglottis and false folds were successively removed and the experiment was repeated for each condition. The subglottal pressure, EGG, flow rate, audio signal, and sound pressure level were recorded during each experiment. Glottal flow resistance was calculated from the pressure and flow signals, while the EGG signal was used to extract fundamental frequency. It was found that these additional structures have positive contribution to the glottal resistance and sound intensity of the larynx. Also, vocal fold elongation and glottal medial compression caused an increase in the glottal resistance. [Work supported by NIDCD Grant No. DC03566.]

A photoglottographic (PGG) method with external lighting and sensing

Photoglottography (PGG) is a moderately invasive technique to observe glottal movements and vocal-fold vibrations. A light guide is inserted into the pharynx and transglottal light is detected by a photosensor placed on the outer skin below the glottis, or conversely the sensor is placed inside the pharynx and the subglottal cavity is illuminated from outside with a light source. This report evaluates a noninvasive PGG method, in which the hypopharynx is illuminated with a light guide placed on the neck skin at the level between the hyoid bone and thyroid cartilage and a photosensor on the skin near the cricoid cartilage. The light passed through the skin illuminates the lumen of the hypopharynx and the photosensor detects indirect (diffusion) light through the glottis during glottal adduction. Choosing an appropriate location for the light source and photosensor, glottal adduction pattern is observed for voiceless stops and fricatives in low as well as high vowel context. Thus, our diffusion-light PGG potentially overcomes the tongue-position dependency of the detected signals, which has been a major caveat of the conventional PGG methods.

Subglottal pressure and normalized amplitude quotient variation in classically trained baritone singers

The subglottal pressure (Ps) and voice source characteristics of five professional baritone singers have been analyzed and the normalized amplitude quotient (NAQ), defined as the ratio between peak-to-peak pulse amplitude and the negative peak of the differentiated flow glottogram and normalized with respect to the period time, was used as an estimate of glottal adduction. The relationship between Ps and NAQ has been investigated in female subjects in two earlier studies. One of these revealed NAQ differences between both singing styles and phonation modes, and the other, based on register differences in female musical theatre singers, showed that NAQ differed between registers for the same Ps value. These studies thus suggest that NAQ and its variation with Ps represent a useful parameter in the analysis of voice source characteristics. The present study aims at increasing our knowledge of the NAQ parameter further by finding out how it varies with pitch and Ps in professional classically trained baritone singers, singing at high and low pitch (278 Hz and 139 Hz, respectively). Ten equally spaced Ps values were selected from three takes of the syllable [pae:], initiated at maximum vocal loudness and repeated with a continuously decreasing vocal loudness. The vowel sounds following the selected Ps peaks were inverse filtered. Data on peak-to-peak pulse amplitude, maximum flow declination rate and NAQ are presented.

Source spectra for excised and latex phonatory models

An excised larynx model and a latex physical model were used to study acoustic spectra of the phonatory source as a function of subglottal pressure, glottal adduction, and vocal-fold length. A supraglottal vocal tract was not used, indicating that the acoustic signal corresponded to the output glottal flow. Each model was mounted over an -inch tracheal tube through which flowed pressurized, heated, and humidified air. The subglottal pressure and EGG signal (excised model) were recorded on a personal computer. The mean flow rate, mean subglottal pressure, and SPL were recorded manually, and adduction was specified by the use of interarytenoid shims. The output audio signals from the larynx models were recorded on a DAT recorder. Spectral information of the audio signal was obtained via FFT analysis (Matlab). Preliminary data indicate that the spectral slope did not have a constant dB/octave rate, and spectral slope had a primary dependence on subglottal pressure and a secondary dependence on adduction. Other acoustic details and the differences between the two models will be discussed. [Work supported by NIDCD Grant Number DC03566.]

Estimating perceived phonatory pressedness in singing from flow glottograms

SummaryThe normalized amplitude quotient (NAQ), defined as the ratio between the peak-to-peak amplitude of the flow pulse and the negative peak amplitude of the differentiated flow glottogram and normalized with respect to period time, has been shown to be related to glottal adduction. Glottal adduction, in turn, affects mode of phonation and hence perceived phonatory pressedness. The relationship between NAQ and perceived phonatory pressedness was analyzed in a material collected from a professional female singer and singing teacher who sang a triad pattern in breathy, flow, neutral, and pressed phonation in three different loudness conditions (soft, middle, loud). In addition, she also sang the same triad pattern in four different styles of singing, classical, pop, jazz, and blues, in the same three loudness conditions. A panel of experts rated the degree of perceived phonatory press along visual analogue scales. Comparing the obtained mean rated pressedness ratings with the mean NAQ values for the various triads showed that about 73% of the variation in perceived pressedness could be accounted for by variations of NAQ.