The influence of water resistance therapy on vocal fold vibration: a high-speed digital imaging study

Effects of the Water Resistance Therapy Program on Behavioral Dysphonia: A Physiological Therapeutic Proposal Based on the Principles of Sensorimotor Learning

INTRODUCTION

The main goal of voice therapy is to reestablish the balance of the vocal system through myoelastic and aerodynamic forces. Therefore, the therapeutic method must focus on vocal physiology as a way of reversing the pathology and also be easy for the patient to internalize it. Water resistance therapy (WRT) can meet this demand. In addition, the use of sensorimotor learning (SML) principles can benefit the rehabilitation process. Then, the objectives of this study are to propose a therapeutic program based on the physiological approach and the principles of SML and to verify its effects on individuals diagnosed with behavioral dysphonia.

METHODS

Experimental, prospective, and analytical study. Participants in this study were 11 volunteers, aged between 18 and 50 years, with vocal complaints and changes, which constituted a diagnosis of behavioral dysphonia. The volunteers underwent intervention with the WRT Program (with a silicone tube submerged in water), consisting of eight sessions lasting 30 minutes. The following SML principles were adopted: prepractice, practice amount, practice distribution, practice variability, practice schedule, attentional focus, and target complexity. To analyze the effect of the WRT Program, vocal economy and its components, cepstral peak prominence-smoothed (CPPs), alpha ratio, L1-L0, and the vocal and laryngopharyngeal symptoms intensity, the Vocal Fatigue Index (VFI) and the Voice Symptom Scale (VoiSS) were measured before and after the interventions. Data were analyzed using the paired t test and Wilcoxon Test (P < 0.05).

RESULTS

The WRT Program showed an increase in the vocal economy (P = 0.004) and a reduction in the glottal contact quotient (P > 0.001). About acoustic measurements, they did not show statistically significant changes. However, concerning the vocal and laryngopharyngeal symptoms intensity, there was a decrease in "breaking voice" (P = 0.019), "hoarseness" (P = 0.003), "pain when speaking" (P = 0.021), and "strained speaking" (P = 0.005). Furthermore, there was a reduction in VoiSS (P = 0.001) as well as VFI in its total value (P = 0.001) and its subscale "physical discomfort associated with the voice" (P = 0.06).

CONCLUSION

The WRT Program, as proposed, has positive effects on voice economy and vocal comfort.

The Effect of Water Resistance Therapy on the Impulse Dispersion of Aerosols During Sustained Phonation

INTRODUCTION

Group singing has been associated with higher transmission risks via exhaled and spread aerosols in the CoVID19 pandemic. For this reason, many musical activities, such as rehearsals and lessons, but also voice therapy sessions, have been restricted in many countries. Consequently, transmission risks and pathways have been studied, such as aerosol amounts generated by exhalation tasks, convectional flows in rooms, or the impulse dispersion of different kinds of phonation. The use of water resistance exercises such as those utilizing LAX VOX®, are common in voice lessons and as vocal warm-ups. With this context, this study investigates the impulse dispersion characteristics of aerosols during a voiced water resistance exercise in comparison to normal singing.

METHODS

Twelve professional singers (six male, six female) were asked to phonate a stable pitch through a silicone tube into a bottle filled with water, holding the end of the tube 5 cm below the surface. Before performing the tasks, the singers inhaled the vapor consisting of 0.5 L base liquid from an e-cigarette. The exhaled gas cloud coming out of the bottle was recorded in all three spatial directions and the dispersion was measured as a function of time.

RESULTS

At the end of the phonation task, the median distance to the front was 0.55 m and the median of the lateral expansion of the cloud was 0.89 m, the maximum to the front reached 0.88 m, and the maximum of lateral expansion 1.05 m. For the upwards direction of the clouds a median of 1.00 m and a maximum of 1.34 m from the mouth were measured. Three seconds after the end of the task, the medians were declining.

CONCLUSION

The exhaled aerosol cloud can expand despite the obstacle of the water when using LAX VOX® during phonation.

Mapping of the Execution of Resonance Tubes Phonation Immersed in Water Exercise in Adults: A Scoping Review

OBJECTIVE

To map the execution of resonance tubes phonation immersed in water exercise in adults with healthy or altered voices.

METHODS

This study was a scoping review. An electronic search was performed using the following databases: MEDLINE, LILACS, SCOPUS, Web of Science, EMBASE, Cochrane Library, gray literature, and a manual search. A blinded review was performed by two authors to determine the selection and extraction procedures. Studies with adult participants with dysphonic or healthy voices who underwent intervention with phonation in a resonance tube immersed in water in the context of the vocal clinic, with an experimental intervention, quasi-experimental, or before and after the intervention were included. Data from the publication, sample, execution, and results obtained from the exercises were extracted by two blinded reviewers. Disagreements were resolved through consensus. The analysis was performed quantitatively.

RESULTS

A total of 44 publications were analyzed. Among these, Brazilian studies were the most frequent, with a publication peak in 2020. The characterization of the sample was variable, with a higher frequency of participants of both sexes who were not voice professionals. The most frequent studies were before and after exercise with a resonance tube immersed in water, in one session, with an exercise execution time of 3 minutes; in cases of more than one series of executions, the 30-sseconds rest time was more frequent. The most used resonance tube was a flexible silicone tube, with a wall thickness of 0.1 mm, immersion container in a 500-, 510-, or 600-mL bottle, 2/3 filled with water, and the resonance tube immersed 2 cm from the water surface. The most used phonatory task was flow phonation with rounded lips similar to the articulation of the vowel /u/. Acoustic analysis and vocal self-assessment are the most commonly used outcome measures. The best results were obtained in the self-assessment.

CONCLUSION

There is significant variability in the information on the execution of resonance tubes phonation immersed in water exercise influenced by vocal diagnosis and experience with previous vocal training. Studies on the effects of this exercise have been concentrated over the last decade and are of the vocal training and therapy. Acoustic and self-assessment measures were used to verify the results, with self-assessment being the outcome that most frequently indicated positive results.

Effect of Varied Tube Phonation in Water Exercises on Nasometric and Electroglottographic parameters: Modification in Terms of Fluid Density and Tube Submerged Depth

OBJECTIVE

Within the scope of semi-occluded vocal tract exercises (SOVTEs), we aimed to examine the effects of four exercise combinations, which involved various fluid densities and tube submersion depths, on acoustic and electroglottographic (EGG) parameters.

METHODS

Four procedures (P) were applied consecutively to 30 female participants with normal voices using different tube submersion depths and fluid densities, including P1 (2 cm, water), P2 (2 cm, nectar), P3 (10 cm, water), and P4 (10 cm, nectar). Nasometric (Nasometer II model 6450) and EGG (Electroglottograph model 6103) measurements were taken before the procedures were initiated (pre-test) and at the end of each procedure. In addition, EGG measurements were taken for each procedure during the application.

RESULTS

For all three velar positions (oral passage, oro-nasal passage, nasal passage), the only procedure that caused a significant change compared to the pre-test stage in regard to nasalance score was P2 (2 cm nectar) in common. All other procedures except P1 (2 cm water) significantly increased velar closure compared to pre-test levels. However, when the differences between the exercises were examined, the least velar closure, compared to the other procedures, was obtained after P4 (10 cm nectar). While there was no significant difference between the procedures in the EGG measurements during the exercise, a significantly higher tendency to contact was observed after the procedures with a denser consistency, and an increase in the fundamental frequency (fo) values occurred in the pairwise comparisons of the procedures in the measurements after the exercises.

CONCLUSION

In SOVTEs in which water phonation is performed with a tube, the use of a fluid with a consistency denser than water can be considered a particularly promising approach. In addition, exercises performed with increasing consistencies in 2 cm depth can provide more vocal cord and velopharyngeal port closure by increasing EGG-CQ and nasalance score values. However, more care should be taken while increasing the consistency at a submersion depth of 10 cm.

Glottal Imaging Study Comparing Vowel Phonation with Semioccluded Vocal Tract Exercises (SOVTEs) Produced Loudly

OBJECTIVES

This study aimed to estimate vocal loading in loud phonation of a vowel and two widely used semiocclusion voice exercises (SOVTEs). Impact stress (IS) was estimated from glottal closing speed, inertial forces from the second derivative of glottal opening and closing.

STUDY DESIGN

Experimental study in vivo.

METHODS

A vocally healthy male sustained the [o:] vowel with habitual loudness and loudly: (1) without a tube, (2) into a silicone "Lax Vox" type tube (35 cm in length, 10 mm in diameter) outer end submerged 10 cm in water, and (3) into a straw (length 12.6 cm, diameter 2.5 mm) the outer end in air. He tried to use equal effort in all loud samples. High-speed video-laryngo-endoscopy was performed with a rigid scope. Oral air pressure (Poral) was registered in a mouthpiece through which the endoscope was inserted into the larynx and to which the tubes were attached air-tightly.

RESULTS

Compared with vowel phonation at habitual loudness, mean of maximal glottal width (max GW) increased by 44.1% for loud tube phonation and decreased by 1.8% for loud straw phonation, and mean absolute value of minimum GW time derivative dmin increased by 57.1% for tube and by 29.5% for straw suggesting faster glottal closing. Compared with loud vowel phonation, max GW increased by 22.6% for loud tube phonation, while it decreased by 16.6% for loud straw phonation. For the tube, dmindecreased by 7.6% and for the straw by 23.8%. Maximal acceleration (ACC) and deceleration (DC) values were larger for the tube and smaller for the straw than the values for both vowel phonations.

CONCLUSIONS

IS, deduced from dmin, increased in loud SOVTEs compared to vowel phonation at a conversational loudness, but remained lower in loud SOVTEs than in loud vowel phonation, particularly with a narrow straw, which also reduced inertial forces, as suggested by the reduced ACC and DC.

Extrinsic Laryngeal Muscle Activity With Different Diameters and Water Depths in a Semi-Occluded Vocal Tract Exercise

PURPOSE

Surface electromyography (sEMG) has been used to evaluate extrinsic laryngeal muscle activity during swallowing and phonation. In the current study, sEMG amplitudes were measured from the infrahyoid and suprahyoid muscles during phonation through a tube submerged in water.

METHOD

The sEMG amplitude values measured from the extrinsic laryngeal muscles and the electroglottographic contact quotient (CQ) were obtained simultaneously from 62 healthy participants (31 men, 31 women) during phonation through a tube at six different depths (2, 4, 7, 10, 15, and 20 cm) while using two tubes with different diameters (1 and 0.5 cm).

RESULTS

With increasing depth, the sEMG amplitude for the suprahyoid muscles increased in men and women. However, sEMG amplitudes for the infrahyoid muscles increased significantly only in men. Tube diameter had a significant effect on the suprahyoid sEMG amplitudes only for men, with higher sEMG amplitudes when phonating with a 1.0-cm tube. CQ values increased with submerged depth for both men and women. Tube diameter affected results such than CQ values were higher for men when using the wider tube and for women with the narrower tube.

CONCLUSIONS

Vocal fold vibratory patterns changed with the depth of tube submersion in water for both men and women, but the patterns of muscle activation differed between the sexes. This suggests that men and women use different strategies when confronted with increased intraoral pressure during semi-occluded vocal tract exercises. In this study, sEMG provided insight into the mechanism for differences between vocally normal individuals and could help detect compensatory muscle activation during tube phonation in water for people with voice disorders.

Acoustic Effects of Vocal Warm-Up: A 7-Week Longitudinal Case Study

OBJECTIVE

A case study was used to determine which acoustic parameters would be sensitive to a SOVT-based vocal warm-up over the duration of a standard voice treatment.

METHODS

The longitudinal research design consisted of repeated voice measures during 7 weeks from a single subject, a 48-year-old male occupational voice user with a history of voice disorders. A steady phonation and running speech tasks were performed before and after an intensive 1-minute water-resistance voice exercise (WRT). Acoustic assessment of the pre-and postrecordings from each session was obtained with freely accessible software (e.g., Audacity, PRAAT) and acoustic measures (e.g., fundamental frequency, jitter, shimmer, alpha ratio, NHR, HNR, L1L0, Cepstral Peak Prominence smoothed).

RESULTS

After WRT, the analysis indicated that jitter, shimmer, and NHR had a small but statistically significant decrease, while alpha ratio, CPPS, and HNR had a statistically significant increase. For the days where there were six repetitions, there was a larger effect in the later repetitions in the day for some metrics (i.e., alpha ratio, shimmer, NHR, CPPS), while others had the biggest effect in the first two repetitions in a day (i.e., jitter, HNR).

CONCLUSIONS

A short vocal water-resistance voice task had a positive effect on the short-term acoustic voice metrics after each repetition of the exercise, independent of the number of repetitions throughout the day. When five repetitions of this exercise routine occurred, there was a more substantial influence on the proportion of acoustic voice changes.

Immediate and Short-term Effects of Straw Phonation in Air or Water on Vocal Fold Vibration and Supraglottic Activity of Adult Patients with Voice Disorders Visualized with Strobovideolaryngoscopy: A Pilot Study

Purpose The first purpose of this study was to investigate and compare the short-term effects after a semi-occluded vocal tract (SOVT) therapy session consisting of straw phonation (SP) in air or water on vocal fold vibration and supraglottic activity of adult patients with voice disorders, visualized with strobovideolaryngoscopy (SVL). The second purpose of this study was to investigate and compare immediate changes in the patients' vocal fold vibration and supraglottic activity during SP in air or water, visualized with SVL. Methods Twelve adult patients with voice disorders (eight women and four men, mean age 52 years) were assigned randomly to one of two study groups: SP in air or SP in water. Immediately before and after a therapy session of 15 min, participants underwent a rigid SVL to determine the short-term effects of the SP session. At the posttherapy examination, flexible SVL while performing SP was added to determine the effects occurring during SP. The visual-perceptual ratings were performed blindly and in random order by three laryngologists, using the Voice-Vibratory Assessment with Laryngeal Imaging rating form for stroboscopy. ResultsShort-term effects after SP: After the SP-in-air session, the supraglottic mediolateral compression decreased significantly. The SP-in-water session led to significantly increased left vibrational amplitude. Immediate effects during SP: During SP in air, a significantly increased left amplitude and mucosal wave, and significantly decreased mediolateral supraglottic activity, were found. SP in water tended to decrease the vibrational amplitude during performance of the task. A trend toward higher anteroposterior supraglottic compression was observed during both SP in air and water, being more prominent in the latter. Conclusion SP in air led to less false vocal fold adduction and consequently less hyperfunction. The small increment in anteroposterior supraglottic activity during SP in air and water might be related to epilarynx narrowing, an economic phenomenon associated with SOVT exercises. The effects on vibrational amplitude were rather ambiguous. The small reduction in amplitude during SP in water is expected to diminish vocal fold impact stress and therefore creates an ideal basis for voice therapy. The increment in amplitude and mucosal wave during SP in air might indicate insufficient supraglottic pressure to obtain the favorable effects of semi-occlusion. Whether or not the rise in amplitude after the SP-in-water session is due to voice efficiency or voice fatigue remains unknown. Future larger-scale investigation in subgroups of voice patients is needed to explore these hypotheses.

Volitional and Non-volitional Devices Used in Voice Therapy and Training: A Scoping Review-Part A

OBJECTIVE

To map the volitional and non-volitional devices used by speech and language pathologists (SLPs) in voice training and therapy and characterize their use in research on voice interventions.

METHODS

This scoping review is the first part of a larger study. The electronic search was carried out by mapping the references in PubMed/Medline, LILACS/BVS, Scopus, Web of Science, EMBASE, and the Cochrane Library, and the manual search was carried out in the grey literature. Two blind independent reviewers selected and extracted data; divergences were solved by consensus. The data extracted in this part of the study were the authorship and year of publication, country, study design, sample characteristics, intervention modality, ingredient, target, mechanism of action, dosage, and outcome measures. They were addressed with descriptive analysis.

RESULTS

Publications that use devices as ingredients are mostly from the last two decades, mainly carried out in the United States of America and Brazil, in adults of both sexes with behavioral dysphonia. Forty-two types of devices were used, many of them with similar approaches but different nomenclatures. Most devices were used voluntarily, focusing on vocal function, and aiming to increase source and filter interaction. Most studies used silicone tubes. The most reported technical specification to apply the ingredient was surface electrodes on the neck. Device dosage was time-controlled, and the most used outcomes were self-assessment and acoustic analysis.

CONCLUSION

Devices are currently used as ingredients in vocal interventions, with a greater focus on increasing the source and filter interaction, associated with silicone tubes (the most used devices in these studies), which have been dosed with performance time. Outcomes were measured with self-assessment instruments.

The Role of the Vocal Tract's Acousto-Mechanical Resonance on the Mechanism of Bubble Release From Tubes Used in SOVTE

AND OBJECTIVES

Semi-occluded vocal tract exercises involving a tube with a distal end immersed in water have been used as a voice rehabilitation technique for nearly 60 years. Advantages of this technique include a constant flow resistance, which is mainly dependent on the tube's immersion depth, and an oscillatory component of the back pressure due to bubble release, which is assumed to provide relief of muscle hypertension around the laryngeal and pharyngeal regions. The goal of this study is twofold. First, to shed more light on the contribution of geometrical parameters, such as tube inner diameter and inclination, on the amplitude of the back pressure oscillation and on the bubble release frequency (BRF). The second goal aims to understand the role of vocal tract compliance on the mechanism of bubble release. We hypothesize that the low-frequency acousto-mechanical resonance of a real compliant vocal tract becomes strongly coupled with the mechanism of bubble release, thereby augmenting the back pressure oscillation and dictating the BRF.

METHODS

The BRF and the back pressure are assessed experimentally as a function of flow rate for tubes with a non-compliant upstream condition, considering different diameters and inclinations. These results are compared with theoretical predictions and the experimental data obtained with six adult subjects, from which the vocal tract acousto-mechanical resonance frequencies are also assessed.

RESULTS

The results obtained with tubes involving a non-compliant upstream condition agreed well with the theoretical results and did not indicate a significant influence of the inclination nor the inner diameter on the BRF and on the oscillatory component of the back pressure. Despite the good agreement with the theory, the results obtained from the tube with a non-compliant upstream termination diverged significantly from those obtained with human subjects. In the latter case, the back pressure fluctuation was considerably higher and the BRF measured for each subject coincided with the frequency associated their respective vocal tract acousto-mechanical resonance.

CONCLUSIONS

Results indicate that the BRF is essentially driven by the acousto-mechanical resonance of the vocal tract. Furthermore, the substantial increase on the amplitude of the oscillatory component of the back pressure suggests a strong feedback loop between the source of pressure (bubble release mechanism) and the resonator (vocal tract). The high-pressure fluctuations within the oral cavity implies that subjects need a considerable extra effort to adjust their vocal tract in order to achieve an adequate impedance match between vocal folds and vocal tractsd to produce voice.

Immediate effects of a semi-occluded water-resistance ventilation mask on vocal outcomes in women with dysphonia

INTRODUCTION

Semi-occluded vocal tract exercises (SOVTEs) are frequently used exercises in voice therapy. An important shortcoming to most SOVTEs is the inability to include continuous speech in these exercises. A variation of water-resistance therapy (WRT), during which a patient phonates through a resonance tube ending in water, was developed to include continuous speech: the semi-occluded water resistance ventilation mask (SOVM-WR). The current study investigated the immediate effects of this innovative technique on vocal outcomes of women with dysphonia.

METHODS

A pretest-posttest randomized controlled trial was performed. Twenty female participants were randomly assigned to the experimental SOVM-WR group or the WRT (control) group. A blinded multidimensional voice assessment was conducted before and after a 30-minute therapy session with the assigned technique.

RESULTS

No significant changes were found in acoustic or auditory-perceptual vocal outcomes in either of the groups, except for a significant increase in lowest frequency in both groups. Patient-reported outcomes (PROMs) showed significant improvements of vocal comfort, vocal effort, and voice quality in both groups, and participants indicated that they would use the techniques at home.

CONCLUSIONS

The similar results of the SOVM-WR to WRT and promising PROMs confirm its suitability as an alternative to the latter technique. Potential reasons for a lack of improvement of objective and auditory-perceptual vocal outcomes are vocal fatigue, tube dimensions and immersion, and the small sample size. Large-scale and longitudinal research is needed to examine whether the SOVM-WR has a higher transfer to spontaneous speech than WRT after a full therapy program.

Immediate effects of straw phonation in air or water on the laryngeal function and configuration of female speech-language pathology students visualised with strobovideolaryngoscopy: A randomised controlled trial

BACKGROUND

A promising way to obtain vocal economy and efficiency is by semi-occluding the vocal tract while phonating. Current knowledge about the immediate effects of semi-occluded vocal tract (SOVT) phonation on the laryngeal function and configuration is based mainly on computer modelling or excised larynges studies. In in vivo SOVT studies, electroglottography (EGG) has been the most commonly used laryngeal outcome, showing contradictory results between studies. Therefore, exploring these aspects by direct visualisation of the human larynx during SOVT phonation using strobovideolaryngoscopy (SVL) is needed.

AIMS

The aim of this study was to investigate and compare the immediate effects of straw phonation (SP) in air, SP in 2 cm water, and SP in 5 cm water (with stirring straws), on the laryngeal function and configuration of a homogeneous group of vocally healthy female speech-language pathology students, visualised with flexible SVL.

METHODS & PROCEDURE

A randomised controlled trial was used. Fifty-two female speech-language pathology students (mean age: 18.7 years, SD: 0.6) were assigned randomly to one of three experimental groups or a control group: (1) SP in air, (2) SP in 2 cm water, (3) SP in 5 cm water or (4) [u] phonation with similar soft onset and slightly pursed lips as in SP but without a straw (control group). The participants underwent flexible SVL during habitual [u] phonation, followed by the specific SOVT exercise of their group assignment. All video samples were evaluated randomly and blindly by two experienced investigators using the Voice-Vibratory Assessment with Laryngeal Imaging (VALI) rating form, first independently and then by consensus.

OUTCOME & RESULTS

Compared to habitual phonation, the vibrational amplitude decreased during SP in 5 cm water and SP in 2 cm water, being more prominent in the first, more flow-resistant exercise. The mucosal wave also decreased during SP in 5 cm water. The anteroposterior (AP) supraglottic compression similarly increased during SP in air, SP in 2 cm water, and SP in 5 cm water. Further, a rise in mediolateral (ML) compression and a decrease in phase symmetry and regularity were found during SP in 2 cm water. A similar decrease in regularity was observed during SP in 5 cm water.

CONCLUSIONS & IMPLICATIONS

Both SP in air and SP in water cause positive immediate laryngeal effects for voice training opportunities. More AP supraglottic activity found during each SP exercise might indicate epilarynx narrowing, an economic phenomenon associated with SOVT. Immersing the straw in water additionally diminished the vibrational amplitude, lowering vocal fold impact stress and risk for phonotrauma during the exercise. The decreased regularity of the vibrational cycles during SP in water might be due to the varying back pressure created by the water bubbling. The impact of SP in water on ML supraglottic compression needs further investigation.

WHAT THIS PAPER ADDS

What is already known on the subject A promising way to obtain vocal economy and efficiency is by semi-occluding the vocal tract while phonating. Current knowledge about the immediate effects of semi-occluded vocal tract (SOVT) phonation on the laryngeal function and configuration is based mainly on computer modelling or excised larynges studies. In in vivo SOVT studies, electroglottography (EGG) has been the most commonly used laryngeal outcome, showing contradictory results between studies. Therefore, exploring these aspects by direct visualisation of the human larynx during SOVT phonation using strobovideolaryngoscopy (SVL) is needed. What this paper adds to existing knowledge Group results of the current study generally support earlier computer modelling and in vivo studies, strengthening the current SOVT knowledge. Both SP in air and SP in water cause positive immediate laryngeal effects for voice training opportunities. More anteroposterior (AP) supraglottic activity found during each SP exercise might indicate epilarynx narrowing, an economic phenomenon associated with SOVT. Immersing the straw in water additionally diminished the vibrational amplitude, lowering vocal fold impact stress and risk for phonotrauma during the exercise. The decreased regularity of the vibrational cycles during SP in water might be due to the varying back pressure created by the water bubbling. The impact of SP in water on ML supraglottic compression needs further investigation. What are the potential or actual clinical implications of this work? Current results support that both SP in air and SP in water can be useful exercises in voice training. SP in water has shown the additional gain of lowering the vibrational amplitude during the exercise, hence supporting its appropriateness for vocal warm-ups by minimising vocal fold impact stress and the risk of phonotrauma. In the future, large-scale randomised controlled trials in other subgroups of voice users, including dysphonic patients, are needed to support evidence-based practice. SVL can facilitate the search for individualised training and therapy approaches.

Optimizing Diameter, Length, and Water Immersion in Flow Resistant Tube Vocalization

OBJECTIVE

The objective was to quantify the range of airflow resistance and oral pressure attainable with variation of length, diameter, and water immersion depth of tubes and straws.

STUDY DESIGN

Pressure-flow equations for tubes, determined previously for variable tube geometries, were used to calculate oral pressure ranges. Human subjects were then recruited to use the variable tube geometries to produce oral pressures, which were quantified with commercial manometers.

RESULTS

Nomograms for airflow resistances and oral pressures are plotted as a function of tube length, tube diameter, and water insertion depth.

CONCLUSIONS

It is shown that tube diameters in the range of 2.5-3.0 mm with tube lengths of 10-40 cm produce oral pressures in the range of 10-40 cm H2O. Insertion of the distal end into water adds a pressure in the amount of the depth of insertion. Maximum power transfer with different tube geometries is discussed.

Quantification of Respirable Aerosol Particles from Speech and Language Therapy Exercises

INTRODUCTION

Voice assessment and treatment involve the manipulation of all the subsystems of voice production, and may lead to production of respirable aerosol particles that pose a greater risk of potential viral transmission via inhalation of respirable pathogens (eg, SARS-CoV-2) than quiet breathing or conversational speech.

OBJECTIVE

To characterise the production of respirable aerosol particles during a selection of voice assessment therapy tasks.

METHODS

We recruited 23 healthy adult participants (12 males, 11 females), 11 of whom were speech-language pathologists specialising in voice disorders. We used an aerodynamic and an optical particle sizer to measure the number concentration and particle size distributions of respirable aerosols generated during a variety of voice assessment and therapy tasks. The measurements were carried out in a laminar flow operating theatre, with a near-zero background aerosol concentration, allowing us to quantify the number concentration and size distributions of respirable aerosol particles produced from assessment/therapy tasks studied.

RESULTS

Aerosol number concentrations generated while performing assessment/therapy tasks were log-normally distributed among individuals with no significant differences between professionals (speech-language pathologists) and non-professionals or between males and females. Activities produced up to 32 times the aerosol number concentration of breathing and 24 times that of speech at 70-80 dBA. In terms of aerosol mass, activities produced up to 163 times the mass concentration of breathing and up to 36 times the mass concentration of speech. Voicing was a significant factor in aerosol production; aerosol number/mass concentrations generated during the voiced activities were 1.1-5 times higher than their unvoiced counterpart activities. Additionally, voiced activities produced bigger respirable aerosol particles than their unvoiced variants except the trills. Humming generated higher aerosol concentrations than sustained /a/, fricatives, speaking (70-80 dBA), and breathing. Oscillatory semi-occluded vocal tract exercises (SOVTEs) generated higher aerosol number/mass concentrations than the activities without oscillation. Water resistance therapy (WRT) generated the most aerosol of all activities, ∼10 times higher than speaking at 70-80 dBA and >30 times higher than breathing.

CONCLUSIONS

All activities generated more aerosol than breathing, although a sizeable minority were no different to speaking. Larger number concentrations and larger particle sizes appear to be generated by activities with higher suspected airflows, with the greatest involving intraoral pressure oscillation and/or an oscillating oral articulation (WRT or trilling).

Analysis of the Immediate Effects of the LaxVox Technique on Digital Videokymography Parameters in Adults With Voice Complaints

OBJECTIVES

Digital videokymography based on high-speed videoendoscopy enables the evaluation of therapeutic techniques and voice training, such as the LaxVox technique, on vocal fold vibrations. This study investigated the immediate effects of the LaxVox technique on digital videokymographic parameters obtained through high-speed videolaryngoscopy in adults with voice complaints.

STUDY DESIGN

An experimental intrasubject comparative study of adults with voice complaints was conducted.

METHODS

Image processing software was used to analyze the videos and obtain digital videokymography parameters. The intraclass correlation coefficient was used to determine the intra-rater reliability of the analyzed parameters. The paired t test and Wilcoxon signed-rank test were used to compare digital videokymography parameters before and after the LaxVox technique, in sex-specific analyses. The significance level was set at 5%.

RESULTS

In total, 25 laryngeal images from 15 women and 10 men were analyzed. On digital videokymography analysis, the mean vocal fold opening in the posterior glottal region was decreased immediately after using the LaxVox technique in women. In contrast, no significant changes were found in other parameters compared to pre LaxVox technique values in both men and women with voice complaints.

CONCLUSION

Digital videokymography analysis revealed that the LaxVox technique reduces the mean vocal fold opening in the posterior glottal region of women with voice complaints.

Finite element modeling of the effects of velopharyngeal opening on vocal tract reactance in female voice

Classical singers use nasal consonants as "resonance exercises," and experimental results have shown that singers may use some velopharyngeal opening (VPO), most often in [a:] and more seldom in [i:] or [u:]. In particular, male singers have been found to increase VPO as pitch rises toward register change frequencies (passaggi). Laryngoscopic findings have shown that some VPO stabilizes vocal fold vibration; the effect is related to positive reactance. This study investigates the effects of VPO on vocal tract (VT) reactance over the range of fundamental frequencies (f₀) used in singing using a computerized tomography-based finite element model of the VT and nose of a female. According to the results, by raising the lowest VT resonances, the VPO increased the VT reactance in the frequency ranges 207-359 Hz for [i:], 265-411 Hz for [u:], and 500-611 Hz for [a:], depending on the VPO size (full or half VPO). These frequency ranges are close to the first and second passaggio of a female singer. The change may have an especially practical stabilizing effect for [a:], which is otherwise characterized by very large changes in VT reactance and negative reactance at the second passaggio.

A Portable Smartphone-Based Laryngoscope System for High-Speed Vocal Cord Imaging of Patients With Throat Disorders: Instrument Validation Study

Background

Currently, high-speed digital imaging (HSDI), especially endoscopic HSDI, is routinely used for the diagnosis of vocal cord disorders. However, endoscopic HSDI devices are usually large and costly, which limits access to patients in underdeveloped countries and in regions with inadequate medical infrastructure. Modern smartphones have sufficient functionality to process the complex calculations that are required for processing high-resolution images and videos with a high frame rate. Recently, several attempts have been made to integrate medical endoscopes with smartphones to make them more accessible to people in underdeveloped countries.

Objective

This study aims to develop a smartphone adaptor for endoscopes, which enables smartphone-based vocal cord imaging, to demonstrate the feasibility of performing high-speed vocal cord imaging via the high-speed imaging functions of a high-performance smartphone camera, and to determine the acceptability of the smartphone-based high-speed vocal cord imaging system for clinical applications in developing countries.

Methods

A customized smartphone adaptor optical relay was designed for clinical endoscopy using selective laser melting–based 3D printing. A standard laryngoscope was attached to the smartphone adaptor to acquire high-speed vocal cord endoscopic images. Only existing basic functions of the smartphone camera were used for HSDI of the vocal cords. Extracted still frames were observed for qualitative glottal volume and shape. For image processing, segmented glottal and vocal cord areas were calculated from whole HSDI frames to characterize the amplitude of the vibrations on each side of the glottis, including the frequency, edge length, glottal areas, base cord, and lateral phase differences over the acquisition time. The device was incorporated into a preclinical videokymography diagnosis routine to compare functionality.

Results

Smartphone-based HSDI with the smartphone-endoscope adaptor could achieve 940 frames per second and a resolution of 1280 by 720 frames, which corresponds to the detection of 3 to 8 frames per vocal cycle at double the spatial resolution of existing devices. The device was used to image the vocal cords of 4 volunteers: 1 healthy individual and 3 patients with vocal cord paralysis, chronic laryngitis, or vocal cord polyps. The resultant image stacks were sufficient for most diagnostic purposes. The cost of the device including the smartphone was lower than that of existing HSDI devices. The image processing and analytics demonstrated the successful calculation of relevant diagnostic variables from the acquired images. Patients with vocal pathologies were easily differentiable in the quantitative data.

Conclusions

A smartphone-based HSDI endoscope system can function as a point-of-care clinical diagnostic device. The resulting analysis is of higher quality than that accessible by videostroboscopy and promises comparable quality and greater accessibility than HSDI. In particular, this system is suitable for use as an accessible diagnostic tool in underdeveloped areas with inadequate medical service infrastructure.

Vocal tract discomfort in caregivers for the elderly during an interval of the COVID-19 pandemic

BACKGROUND

During the coronavirus disease 2019 (COVID-19) pandemic, professional caregivers caring for the elderly may experience more vocal tract problems in addition to regular high vocal demands while wearing face masks/coverings.

METHODS AND PARTICIPANTS

Vocal tract discomfort (VTD) was assessed in 64 caregivers in one home for the elderly (64% participation rate) in June 2020 using the German version of the VTD scale.

RESULTS

More than one-half of the participating caregivers experienced VTD, described mostly as dryness, irritability, and tightness. Approximately, 80% reported that sensations were not perceived before enhanced infection prevention standards were implemented.

CONCLUSIONS

Among caregivers caring for the elderly during the COVID-19 pandemic, special care should be focused on the voice and vocal tract well-being.

Semi-occluded vocal tract exercises in healthy young adults: Articulatory, acoustic, and aerodynamic measurements during phonation at threshold

Semi-occluded vocal tract exercises (SOVTEs) are increasingly popular as therapeutic exercises for patients with voice disorders. This popularity is reflected in the growing research literature, investigating the scientific principles underlying SOVTEs and their practical efficacy. This study examines several acoustic, articulatory, and aerodynamic variables before, during, and after short-duration (15 s) SOVTEs with a narrow tube in air. Participants were 20 healthy young adults, and all variables were measured at threshold phonation levels. Acoustic variables were measured with a microphone and a neck accelerometer, and include fundamental frequency, glottal open quotient, and vocal efficiency. Articulatory variables were measured with ultrasound, and include measures of the tongue tip, tongue dorsum, and posterior tongue height, and horizontal tongue length. Aerodynamic variables were measured with an intraoral pressure transducer and include subglottal, intraoral, and transglottal pressures. Lowering of the posterior tongue height and tongue dorsum height were observed with gender-specific small changes in the fundamental frequency, but there were no significant effects on the transglottal pressure or vocal efficiency. These findings suggest that the voices of healthy young adults already approach optimal performance, and the continued search for scientific evidence supporting SOVTEs should focus on populations with voice disorders.

Ejercicios de tracto vocal semi-ocluido en la rehabilitación de parálisis recurrenciales: Un estudio de caso

El presente trabajo tiene como propósito mostrar la efectividad de una secuencia de ejercicios de tracto vocal semi-ocluido en la rehabilitación de un caso clínico vocal diagnosticado con parálisis recurrencial unilateral. Los ejercicios de tracto vocal semi-ocluido corresponden a una serie de posturas que involucran alargamientos artificiales o estrechamientos del tracto vocal con la finalidad de aumentar la impedancia y generar cambios favorables en la vibración de los pliegues vocales. Dichos ejercicios están enmarcados dentro de la tendencia de rehabilitación fisiológica la cual busca reestablecer un balance de los tres subsistemas involucrados en la producción de la voz (Respiración-fonación-resonancia) de manera simultánea, contraponiéndose a la tendencia tradicional de abordaje sintomatológico. Por otro lado, la tendencia fisiológica se basa en los principios del aprendizaje sensoriomotor el cual busca reales cambios en el patrón de producción de la voz, y que estos permanezcan en el tiempo. Se realizó terapia vocal durante 15 sesiones con ejercicios de tracto vocal semi-ocluido. Para valorar los cambios en la voz, se realizó una evaluación inicial y final a través de nasofibrolaringoscopía, análisis acústico mediante medidas de perturbación y análisis espectral, estudio perceptual mediante la escala GRBASI valorada por una comisión de jueces externos, tiempos máximos fonatorios y valoración del propio paciente. Posterior al tratamiento se produjeron cambios favorables en la voz y se concluye que los ejercicios de tracto vocal semi-ocluido pueden constituir una herramienta efectiva para el abordaje de este tipo de patologías.

Duration of biodynamic changes associated with water resistance therapy

INTRODUCTION

In current voice research, there is a growing interest in semi-occluded vocal tract exercises and their contribution to an increased vocal efficiency. However, there are only few studies on the lasting effects.

MATERIAL AND METHODS

Eight vocally healthy subjects were asked to sustain a phonation at a comfortable loudness on the vowel /i/, with a Fundamental Frequency of 250 Hz (females) or 125 Hz (males). During phonation the subjects were simultaneously recorded with transnasal High Speed Videoendoscopy (HSV, 20,000fps), electroglottography, and audio signals. The subjects then performed a water resistance therapy (WRT) for 10 min (tube: 30 cm length, 5 cm below water surface, diameter 9 mm). Repeated measurements of sustained phonation were performed 0, 5, 10, 20, and 30 min after exercising. From the HSV material the Glottal Area Waveform (GAW) was segmented and GAW parameters were computed.

RESULTS

There were strong inter-individual differences concerning the changes of different measures over time after WRT. In general, directly after WRT there was a lowering of the GAW derived Period Perturbation Quotient, a lowering of the Closing Quotient and an increase of the Sound Pressure Level (SPL) in comparison to the pre-intervention measurement. However, only 5 min post WRT there was no longer a clear difference compared to baseline results before WRT. Other values such as Open Quotients exhibited no evident changes by WRT at any timepoint.

CONCLUSIONS

WRT showed strong inter-individual effects concerning the changes in the evaluated measures post-intervention. General tendencies of some measures directly after the intervention showed a brief effect of only a few minutes.

Immediate effects of water resistance therapy on patients with vocal fold mass lesions

Introduction

Semi-occluded vocal tract exercises, such as water resistance therapy (WRT), are widely used in voice therapy. However, the potential positive effects of such a therapy on vocal fold oscillation patterns in patients indicating a need for phonomicrosurgery have not yet been explored. The presented study aims to analyze the effect of WRT in patients suffering from vocal fold mass lesions.

Materials and methods

Eight participants with vocal fold mass lesions were asked to sustain a phonation on the vowel /i/ at a comfortable loudness and a fundamental frequency of 250 Hz (females) or 125 Hz (males). During phonation the subjects were simultaneously recorded with transnasal high-speed videoendoscopy (HSV, 20.000 fps), electroglottography, and audio signals. These subjects then performed a WRT (phonation in a silicone tube of 30 cm length, 5 cm below the water surface) for 10 min. Repeated measurements of sustained phonation were performed 0, 10, and 30 min after exercising. From the HSV data the glottal area waveform (GAW) was segmented and GAW parameters were computed.

Results

During WRT there was an increase of the GAW related open quotient and closing quotient. Immediately after WRT, there was a drop of both values followed by a rise of these parameters up to 30 min after the intervention. Furthermore, there was no correlation between GAW and electroglottographical open quotients.

Conclusions

The effects observed after a single session of WRT on participants with vocal fold mass lesions showed a similar pattern to vocal fatigue.

Experimental and Computational Modeling of the Effects of Voice Therapy Using Tubes

Purpose Phonations into a tube with the distal end either in the air or submerged in water are used for voice therapy. This study explores the effective mechanisms of these therapy methods. Method The study applied a physical model complemented by calculations from a computational model, and the results were compared to those that have been reported for humans. The effects of tube phonation on vocal tract resonances and oral pressure variation were studied. The relationships of transglottic pressure variation in time P_trans ( t) versus glottal area variation in time GA( t) were constructed. Results The physical model revealed that, for the phonation on [u:] vowel through a glass resonance tube ending in the air, the 1st formant frequency ( F₁ ) decreased by 67%, from 315 Hz to 105 Hz, thus slightly above the fundamental frequency ( F₀ ) that was set to 90-94 Hz . For phonation through the tube into water, F₁ decreased by 91%-92%, reaching 26-28 Hz, and the water bubbling frequency F_b ≅ 19-24 Hz was just below F₁ . The relationships of P_trans ( t) versus GA( t) clearly differentiate vowel phonation from both therapy methods, and show a physical background for voice therapy with tubes. It is shown that comparable results have been measured in humans during tube therapy. For the tube in air, F₁ descends closer to F₀ , whereas for the tube in water, the frequency F_b occurs close to the acoustic-mechanical resonance of the human vocal tract. Conclusion In both therapy methods, part of the airflow energy required for phonation is substituted by the acoustic energy utilizing the 1st acoustic resonance. Thus, less flow energy is needed for vocal fold vibration, which results in improved vocal efficiency. The effect can be stronger in water resistance therapy if the frequency F_b approaches the acoustic-mechanical resonance of the vocal tract, while simultaneously F₀ is voluntarily changed close to F_1.

Adductory Vocal Fold Kinematic Trajectories During Conventional Versus High-Speed Videoendoscopy

Objective Prephonatory vocal fold angle trajectories may supply useful information about the laryngeal system but were examined in previous studies using sigmoidal curves fit to data collected at 30 frames per second (fps). Here, high-speed videoendoscopy (HSV) was used to investigate the impacts of video frame rate and sigmoidal fitting strategy on vocal fold adductory patterns for voicing onsets. Method Twenty-five participants with healthy voices performed /ifi/ sequences under flexible nasendoscopy at 1,000 fps. Glottic angles were extracted during adduction for voicing onset; resulting vocal fold trajectories (i.e., changes in glottic angle over time) were down-sampled to simulate different frame rate conditions (30-1,000 fps). Vocal fold adduction data were fit with asymmetric sigmoids using 5 fitting strategies with varying parameter restrictions. Adduction trajectories and maximum adduction velocities were compared between the fits and the actual HSV data. Adduction trajectory errors between HSV data and fits were evaluated using root-mean-square error and maximum angular velocity error. Results Simulated data were generally well fit by sigmoid models; however, when compared to the actual 1,000-fps data, sigmoid fits were found to overestimate maximum angle velocities. Errors decreased as frame rate increased, reaching a plateau by 120 fps. Conclusion In healthy adults, vocal fold kinematic behavior during adduction is generally sigmoidal, although such fits can produce substantial errors when data are acquired at frame rates lower than 120 fps.

Immediate Lip Trill Effects on the Standard Diagnostic Measures Voice Range Profile, Jitter, Maximum Phonation Time, and Dysphonia Severity Index

OBJECTIVES

Semi-occluded vocal tract exercises are widely applied to improve vocal performance in speakers, singers, and voice patients. This study investigates immediate lip trill effects on standard voice assessment measures including voice range profiles, jitter, maximum phonation time, and Dysphonia Severity Index in vocally healthy women.

STUDY DESIGN

Experimental study.

SETTING

Otolaryngology clinic within tertiary hospital.

SUBJECTS AND METHODS

Twenty-five vocally healthy women between 19 and 58 years (mean 38.4) were assessed before and after 3 minutes of standardized lip trill training combined with defined voice fundamental frequency and intensity modulations. Main outcome measures were fundamental frequency (F₀) during counting (F₀ counting), the singing voice range profile parameters minimum, maximum and range of F₀ and voice sound pressure level (voice SPL), jitter (%), maximum phonation time (MPT), and the Dysphonia Severity Index (DSI). Wilcoxon signed rank test was applied to determine significant changes after exercise.

RESULTS

After exercise the singing F₀ and SPL range significantly increased from 549 (SD 217) to 612 (238) Hz and 45.1 (10.1) to 47.3 (9.8) dBA, resepctively (P<0.05). Maximum voice SPL significantly increased from 90.9 (10.3) to 94 (9.7) dBA (P<0.05). Mean F₀ during counting showed a highly significant increase from 198 (SD 25.6) to 209 Hz (SD 25.4, P<0.01). No significant changes were found for all other parameters.

CONCLUSIONS

In vocally healthy women, lip trill training immediately facilitates increases in mean F₀ during counting, and singing F₀ and SPL range. Future studies should investigate, if changes to these parameters indicate immediate responsiveness to voice exercise also in voice patients, and if these findings transfer to long-term effects through prolonged training.

Water Resistance Therapy as Vocal Warm-Up Method in Contemporary Commercial Music Singers

BACKGROUND/AIMS

Although water resistance therapy (WRT) has been widely used in voice training, no data are supporting the effectiveness of WRT as vocal warm-up for singers. The present study aimed to determine the effects of WRT as a vocal warm-up method in contemporary commercial music (CCM) singers.

METHODS

Twenty-two CCM singers were randomly assigned to one of two types of 15-min vocal warm-up: open vocal tract (OVT) warm-up and WRT. Self-perceived resonant voice quality and aerodynamic, electroglottographic, and acoustic measures were assessed before, immediately after vocal warm-up, and after 40 min of vocal loading.

RESULTS

Significant results were found immediately after vocal warm-up. Subglottic pressure and inspiratory airflow duration decreased in both groups. SPL decreased for the OVT group. No changes in SPL were found for the WRT group. Significant results were observed after vocal loading. Subglottic pressure and inspiratory airflow duration decreased for both groups after vocal loading. Expiratory airflow duration and electroglottographic contact quotient decreased for the OVT group.

CONCLUSION

Some objective data suggest that the WRT method is more effective as vocal warm-up than OVT exercises. Since outcomes in self-perceived resonant voice quality for both methods were similar but physiological effects were different, vocal warm-up strategies might produce a placebo effect.

Impact Stress in Water Resistance Voice Therapy: A Physical Modeling Study

OBJECTIVES

Phonation through a tube in water is used in voice therapy. This study investigates whether this exercise may increase mechanical loading on the vocal folds.

STUDY DESIGN

This is an experimental modeling study.

METHODS

A model with three-layer silicone vocal fold replica and a plexiglass, MK Plexi, Prague vocal tract set for the articulation of vowel [u:] was used. Impact stress (IS) was measured in three conditions: for [u:] (1) without a tube, (2) with a silicon Lax Vox tube (35 cm in length, 1 cm in inner diameter) immersed 2 cm in water, and (3) with the tube immersed 10 cm in water. Subglottic pressure and airflow ranges were selected to correspond to those reported in normal human phonation.

RESULTS

Phonation threshold pressure was lower for phonation into water compared with [u:] without a tube. IS increased with the airflow rate. IS measured in the range of subglottic pressure, which corresponds to measurements in humans, was highest for vowel [u:] without a tube and lower with the tube in water.

CONCLUSIONS

Even though the model and humans cannot be directly compared, for instance due to differences in vocal tract wall properties, the results suggest that IS is not likely to increase harmfully in water resistance therapy. However, there may be other effects related to it, possibly causing symptoms of vocal fatigue (eg, increased activity in the adductors or high amplitudes of oral pressure variation probably capable of increasing stress in the vocal fold). These need to be studied further, especially for cases where the water bubbling frequency is close to the acoustical-mechanical resonance and at the same time the fundamental phonation frequency is near the first formant frequency of the system.