Effect of variations to a simulated system of straw phonation therapy on aerodynamic parameters using excised canine larynges

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.

Singing In The Mask: Effects Of A Variably Occluded Face Mask On Singing

OBJECTIVE

A limitation of traditional semi-occluded vocal tract exercises (SOVTE) is the single sustained vowel task that precludes co-articulated singing. This study investigated immediate effects of a variably occluded face mask (VOFM) on vocal effort, acoustic, and aerodynamic measures in sung low and high pitches of healthy singers.

DESIGN

Single-group, pre-post intervention study.

METHODS

The outlet ports of disposable anesthesia facemasks were fitted with plastic caps with two drilled openings sizes (9.6 mm, 6.4 mm). Twenty-three singers with no voice complaints provided baseline vocal effort, acoustic, and aerodynamic measures in high and low pitches. Participants trained in four conditions: two VOFM sizes (9.6 mm, 6.4 mm) in combination with the 20th and 80th percentile of the singer's pitch range. Participants were trained on three phonatory tasks: repeated consonant/vowel syllables, sung sentence, and sustained vowel. Vocal effort before and after training was compared using a visual-analog scale, while standardized mean differences captured acoustic and aerodynamic changes before and after training.

RESULTS

Participants reported decreased vocal effort after VOFM training at all occlusion and pitch combinations. On average, consistent beneficial effect sizes were found in cepstral peak prominence (CPP) and cepstral spectral index of dysphonia (CSID) for all 4 occlusion-pitch combinations, and vocal intensity and mean estimated subglottal pressure increased for all 4 occlusion-pitch training combinations. Changes in mean phonatory airflow and resistance were less consistent.

DISCUSSION

There was an immediate effect of decreased vocal effort in singing after VOFM training. Acoustic and aerodynamic effects were variable and modest. Future studies should explore changes in these outcomes after VOFM in singing voice therapy.

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.

Acoustic, Aerodynamic, Morphometric, and Perceptual Changes During and After Semi-Occluded Vocal Tract Exercise: An Integrative Review

OBJECTIVE

The body of literature discussing the acoustic, aerodynamic, perceptual, and morphometric changes that occur during and after semi-occluded vocal tract exercise (SOVTE) has dramatically expanded within the past 20 years. The current study integrates the literature on SOVTE from the 1990s onward, reviewing the technique's clinically relevant effects in vocally untrained adults both with and without dysphonia. The study aims to give clinicians actionable information on how SOVTEs alter vocal function in both normal and pathological states.

METHODS

The author queried the MEDLINE database for combinations of search terms related to semi-occluded vocal tract exercise. To improve article identification, the author also performed iterative citation webbing in which the reference lists of each article selected for full-text screening were cross-referenced against the articles returned in the initial MEDLINE search. Articles identified by iterative citation webbing that did not appear in the initial MEDLINE search were then screened individually. The second author independently verified adherence to the review's inclusion and exclusion criteria in both the initial search and data extraction phases.

RESULTS

The initial MEDLINE search returned 869 articles, 111 of which passed the title and abstract screening phase. Iterative citation webbing returned an additional 20 studies, resulting in a total of 131 articles that qualified for full-text screening. 53 articles passed full-text screening and were included in the current review.

DISCUSSION

Semi-occluded vocal tract exercise increases the inertive reactance of the glottis, vocal tract, and air column, as well as introducing flow resistance at the level of the lips or velopharyngeal port. Each of these mechanisms yields downstream acoustic, aerodynamic, morphometric, and perceptual changes, including reductions in phonation threshold pressure and perceived phonatory effort, improved spectral characteristics of the acoustic signal, attenuation of vocal fold impact stress as indexed by various metrics such as maximum area declination rate, and alterations to the physical dimensions of the vocal tract. Although few studies examined the duration of these changes post exercise, several RCTs support the assertion that SOVTE's effects can be sustained with regular practice over weeks or months, regardless of current vocal health status.

Immediate effects of the semi-occluded bubble mask technique using VocalFeel® device as vocal warm-up in singers

OBJECTIVE

The present study aims at investigating the immediate effects of the Semi-Occluded Bubble Mask Technique (SOBM) performed with the device VocalFeel® as a vocal warm-up in a group of professional singers.

STUDY DESIGN

A randomized controlled study was carried out.

METHODS

Forty-four vocally healthy professional singers were randomly divided into two groups on recruitment: an experimental group and a control group. The same vocal warm-up exercise was performed by the experimental group with the SOMB technique and by the control group without semi-occlusion. Self assessments, acoustic analysis and aerodynamic analysis of Peak Nasal Inspiratory Flows (PNIF) and Peak Oral Inspiratory Flows (POIF) were performed.

RESULTS

Significant improvements after the SOBM technique were detected in the experimental group concerning some acoustic parameters (Jitt%; Shimm%) and aerodynamic measures (PNIF and POIF). No significant improvements after the warm-up exercise were observed in the control group. Significant differences between the experimental and the control group were found for ΔJitt%, ΔShimm%, ΔNHR, ΔPOIF and self assessments.

CONCLUSIONS

The results of the present study support the efficacy of a vocal warm-up performed with the SOBM technique using VocalFeel® device in terms of acoustic quality, aerodynamic measures and perceived phonatory comfort in professional singers.

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.

Excised human larynx in N-vinyl-2-pyrrolidone-embalmed cadavers can produce voiced sound by pliable vocal fold vibration

Tissue-hardening effect and health-hazard issue of formaldehyde (FA) have long been a great disadvantage of this conventional fixative in anatomical research. We recently developed a FA-free embalming method for cadavers which utilizes N-vinyl-2-pyrrolidone (NVP) and enables assessment of motion kinetics by maintaining the softness of embalmed tissue. By assessing the feasibility of NVP-embalmed tissue to mimic vocalization, this study aimed to prove the potential of embalmed cadavers, which have previously been used only for the understanding of anatomical morphology, for the assessment of precise motion physiology in the human body. Ten cadavers embalmed in NVP (n = 6) and FA (n = 4) were incorporated in this study. Excised larynges underwent experimental phonation to mimic vocalization with fast and pliable vibration of vocal folds. High-speed digital imaging was utilized for the assessment of vocal fold vibration. Furthermore, acoustic analysis of the voiced sound, and reproducibility examination were also performed. Regular vocal fold vibrations successfully produced voiced sounds during experimental phonation using NVP-embalmed larynges. The vibratory frequency, vibration amplitude, and stretch rate of the vocal folds were comparable to those of living humans. Six months after the first experiment, the vocal parameters were reproduced, to suggest the long-term preservation potential of our NVP-embalming technique. On the other hand, neither voiced sound nor vocal fold vibration were observed in FA-embalmed larynges. This novel embalming technique could pioneer the next era to utilize embalmed cadavers for the examination of motion physiology in the human body.

Efficacy of different straw phonation doses for vocal fatigue prevention

PURPOSE

The aim of the present study was to investigate the efficacy of different straw phonation doses for vocal fatigue (VF) prevention.

METHOD

Thirteen males and 13 females participated in the study. Each participant received seven preventive treatments (i.e. voice rest with hydration for 15 minutes, straw phonation into air or water for one, three and five minutes) in separate visits. Phonatory threshold pressure (PTP) and self-perceived vocal fatigue (PVF) symptoms severity were adopted as the primary and secondary outcome measures, respectively. Measurements were taken before and after the preventive treatment, and after a 90-minute VF-inducing task.

RESULT

PTP was maintained in four of the straw phonation doses, namely; the one-minute into air, one-minute, three-minute and five-minute into water conditions; but not in the voice rest condition. Straw phonation into water of a depth of 5 cm for one minute was considered the optimal dose for VF prevention. PVF, however, was not maintained after VF-inducing task in all treatment conditions.

CONCLUSION

Straw phonation into water for one minute was capable of preventing phonatory efficiency (as measured with PTP) from deteriorating. The dose identified in the present study may be adopted for future prevention studies in population that is vulnerable to VF.

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.

Immediate Effects of a Semi-Occluded Water Resistance Ventilation Mask on Objective and Subjective Vocal Outcomes in Musical Theater Students

Background Traditional semi-occluded vocal tract exercises (SOVTEs) are restricted to single-phoneme tasks due to the semi-occlusion at the mouth, which hinders full articulation, continuous speech, and singing. Innovative SOVTEs should overcome this limitation by creating the semi-occlusion outside the oral cavity. Purpose The purpose of this study was to investigate the immediate effects of a semi-occluded water resistance ventilation mask, which allows for continuous speech and singing, on objective (voice range, multiparametric voice quality indices) and subjective (auditory-perceptual, self-report) vocal outcomes in musical theater students. Method A pre-/posttest randomized controlled trial was used. Twenty-four musical theater students (16 women and eight men, with a mean age of 21 years) were randomly assigned into a study group and a control group. The study group received a vocal warm-up session with the innovative water resistance ventilation mask (tube attached to the mask "outside" the mouth), whereas the control group received the traditional water resistance approach (tube "inside" the mouth). Both sessions lasted 30 min and were similar with respect to vocal demand tasks. A multidimensional voice assessment including objective and subjective outcomes was performed pre- and posttraining by an assessor blinded to group allocation. Results The Dysphonia Severity Index significantly and similarly increased (improved) in both the study and control groups, whereas the Acoustic Voice Quality Index solely decreased (improved) in the control group. The intensity range significantly decreased (worsened) and the semitone range significantly increased (improved) in the study group, whereas no differences in voice range profile were found in the control group. Auditory-perceptually, a more strenuous speaking voice was noticed after the use of the traditional water resistance approach. The subjects perceived both SOVTEs as comfortable vocal warm-up exercises that decrease the amount of effort during speaking and singing, with a slight preference for the water resistance ventilation mask. Conclusions Both the innovative water resistance ventilation mask and the traditional water resistance exercise seem effective vocal warm-up exercises for musical theater students. The additional articulatory freedom of the mask might increase the phonatory comfort and the practical implementation of SOVTEs in the daily vocal warm-up of (future) elite vocal performers. The hypothesis of a higher transfer to continuous speech or singing in the mask condition has not been supported by the current study. Larger scale investigation and longer term follow-up studies are needed to confirm these preliminary results. Supplemental Material https://doi.org/10.23641/asha.11991549.

Effects of Varying Lengths and Diameters During Straw Phonation on an Excised Canine Model

OBJECTIVE/BACKGROUND

Straw phonation, a well-established method of vocal exercise, started over 100 years ago. However, some of the most basic questions about best practices remain including the ideal extension length and the ideal restriction (semiocclusion) diameter. This study aims to help answer these questions by looking at both separately, with all other variables controlled.

METHODS

Four (4) straws with lengths of 5, 25, 50, and 75 centimeters and 4 restrictions with diameters of 3, 9, 15, and 21 mm were tested, separately. They were attached to the end of a simulated vocal tract which was then affixed to an excised canine larynx. Airflow was increased until the larynges achieved self-sustained phonation then aerodynamic, acoustic, and electroglottographic data were collected.

RESULTS

There was a significant decrease in the phonation threshold pressure using the 5 and 25 cm straw lengths and the 9 and 15 mm restrictions. The phonation threshold flow and contact quotient saw insignificant changes, except in the case of the 3 mm restriction.

DISCUSSION

It is theorized that the increased inertive reactance helps to decrease phonation threshold pressure. By controlling for all other variables, the effects of the length or diameter of the straw can be analyzed in isolation. These results narrow the significant range of lengths and diameters used in straw phonation.

Effects of a simulated system of straw phonation on the complete phonatory range of excised canine larynges

PURPOSE

This study investigated the effects of straw phonation therapy on the aerodynamic and acoustic parameters of the vocal folds at different levels of elongation and subglottal pressure.

METHODS

20 excised canine larynges were used in both experimental (straw phonation therapy simulation) and control conditions. Aerodynamic parameters, including phonation threshold pressure (PTP), phonation instability pressure (PIP), phonation pressure range (PPR), phonation threshold flow (PTF), phonation instability flow (PIF), phonation flow range (PFR), were obtained at different levels of vocal fold elongation (0%, 10%, 20%). Acoustic parameters, including fundamental frequency (F0), jitter, shimmer, signal noise ratio (SNR) were detected at different levels of vocal fold elongation (0%, 10%, 20%) and subglottal pressure (15 cmH₂O, 20 cmH₂O, 25 cmH₂O).

RESULTS

Significant decreases in PTP and PTF and significant increases in PIP, PIF, PPR, and PFR occurred in experimental condition at all levels of elongation when compared with control condition. However, no significant changes of acoustic parameters were obtained between conditions at all levels.

CONCLUSION

At different levels of vocal fold elongation, straw phonation not only lowered the onset of normal voice, but also elevated the onset of chaotic voice, indicating a better voice economy and voice control. Moreover, the improved phonatory range demonstrated that straw phonation had the potential to prevent voice users who have high voice demand from voice fatigue and vocal damage.

Effect of three semi-occluded vocal tract therapy programmes on the phonation of patients with dysphonia: lip trill, water-resistance therapy and straw phonation

BACKGROUND

To date, the immediate effects of a semi-occluded vocal tract (SOVT) configuration have been thoroughly demonstrated. However, it is not yet sufficiently confirmed whether a therapy programme (i.e. longer than one session) using SOVT exercises leads to an enhanced phonation and improved vocal quality.

AIMS

The aim of this study was to investigate the effect of three SOVT therapy programmes: lip trill, water-resistance therapy (WRT) and straw phonation, on the vocal quality, vocal capacities, psychosocial impact and vocal tract discomfort of patients with dysphonia.

METHODS & PROCEDURES

A blocked-randomized sham-controlled trial was used. Thirty-five patients with dysphonia (mean age = 21 years; 33 women, two men) were assigned to either a lip trill group, a WRT group, a straw phonation group or a control group using blocked randomization. The lip trill, WRT and straw phonation groups practised their respective SOVT exercise across 3 weeks, whereas the control group received a sham treatment across the same time span. A multidimensional voice assessment consisting of both objective (multiparametric indices: Dysphonia Severity Index (DSI), Acoustic Voice Quality Index (AVQI)) and subjective (subject's self-report, auditory-perceptual evaluation) vocal outcomes was performed by a blinded assessor pre- and post-therapy.

OUTCOMES & RESULTS

Lip trill and straw phonation therapy led to a significant improvement in DSI. Auditory-perceptual grade and roughness significantly decreased after straw phonation. Lip trill and WRT both led to a significant decrease in Voice Handicap Index. Subjects reported a better self-perceived vocal quality and a more comfortable voice production after WRT. No changes were found after the sham treatment in the control group.

CONCLUSIONS & IMPLICATIONS

Results suggest that SOVT therapy programmes including lip trill or straw phonation can improve the objective vocal quality in patients with dysphonia. Auditory-perceptual improvements were found after straw phonation therapy, whereas psychosocial improvements were found after lip trill and WRT. Patients seem to experience more comfort and a better self-perceived vocal quality after WRT. This study supports the use of the three SOVT therapy programmes in clinical practice. They all had a positive impact on one or more outcomes of the multidimensional voice assessment. Strikingly, vocal quality outcomes were not in line with the subject's opinion. Larger-scale investigation is needed to support these preliminary findings.

Immediate Effects of the Semi-Occluded Ventilation Mask on Subjects Diagnosed With Functional Dysphonia and Subjects With Normal Voices

PURPOSE

The present study was designed to assess the immediate effects of the semi-occluded ventilation mask (SOVM) in subjects with functional dysphonia and subjects with normal voice.

METHODS

Sixty-four participants were included in this study (48 women and 16 men). Thirty-one of them were diagnosed with functional dysphonia and 33 with normal voice. All subjects were randomly assigned to one of two conditions: an experimental condition using the SOVM (n = 33) and a control condition with participants not using the SOVM (n = 31). Thus, within both conditions, participants could be either dysphonic or normal-voiced. This produced a total of four different groups: (1) subjects with normal voice with SOVM (n = 17), (2) subjects with normal voice without SOVM (n = 16), (3) dysphonic subjects with SOVM (n = 16), and (4) dysphonic subjects without SOVM (n = 15). All participants underwent aerodynamic, electroglottographic (EGG), and acoustic assessments, and were also asked to assess their own voice, before and after voice exercises.

RESULTS

Significant differences were found for aerodynamic, EGG, and acoustic variables when comparing SOVM conditions (dysphonic and normal) against control. Cepstral peak prominence and EGG contact quotient showed an increase among dysphonic participants with SOVM. L1-L0 showed an increase for all participants in SOVM condition (dysphonic and normal). Self-perceived resonant voice quality showed an increase for both groups in SOVM condition. Glottal airflow showed a decrease for the dysphonic participants in SOVM condition. Phonation threshold pressure and subglottic pressure showed a decrease for both groups in SOVM condition.

CONCLUSION

The present study suggests that immediate positive effect could be produced by connected speech phonatory tasks using the SOVM in both dysphonic subjects and subjects with normal voice, the change being greater among the former. SOVM seems to promote an easy voice production and a more efficient phonation.

Development of Excised Larynx

The larynx is a complex organ which has a role in a variety of functions such as phonation, breathing, and swallowing. To research these functions, it is widely accepted that in vivo studies provide more anatomically and physiologically relevant findings. However, invasive procedures are generally needed to measure variables such a subglottal pressure, vocal fold tension and stiffness, and cricothyroid muscle stretch. Performing studies using excised larynges is a useful technique which makes it possible to not only measure phonation parameters but control them as well. Early studies using excised larynges mainly focused on controlling specific parameters and mathematical modeling simulations. The use of these studies has helped further research in laryngeal anatomy, imaging techniques, as well as aerodynamic, acoustic, and biomechanical properties. Here, we describe the progress of this research over the past 5 years. The number of accepted animal models has increased and ideas from excised larynx studies are starting to be applied to treatment methods for laryngeal disorders. These experiments are only valid for an excised situation and must continue to be combined with animal experimentation and clinical observations.

Establishment and Analysis of False Vocal Folds Hypertrophy Model in Excised Canine Larynges

OBJECTIVE

This study aimed to investigate the role of false vocal folds (FVFs) medialization in phonation and the acoustic impact of ventricular hypertrophy by establishing an FVF hypertrophy model.

STUDY DESIGN

A prospective in vitro experiment was carried out.

SETTING

The study was carried out using a pseudolung platform with high-speed camera in a soundproof room.

MATERIALS AND METHODS

Control, degree I, and degree II FVFs hypertrophy were simulated in 10 excised larynges via fructose injection of 0.1 mL for degree I and 0.25 mL for degree II. Mean flow rate (MFR), fundamental frequencies (F0), formants, and sound pressure level were measured with a subglottal pressure of 1.5 kPa and 2.5 kPa, respectively.

RESULTS

When the subglottal pressure was controlled at both at 1.5 kPa and at 2.5 kPa, the degree of FVF hypertrophy significantly influenced the distribution of the formants, F0, and MFR in excised canine larynges. Increasing the degree of hypertrophy was associated with a decrease in F0 and an increase in MFR. In degree II FVF hypertrophy models, the sound pressure level and the first formant were significantly higher (P < 0.05) than in normal models.

CONCLUSION

Hypertrophy of the FVFs has a significant influence on the distribution of sound energy and is associated with changes in sound quality.

Short-Term Effect of Two Semi-Occluded Vocal Tract Training Programs on the Vocal Quality of Future Occupational Voice Users: "Resonant Voice Training Using Nasal Consonants" Versus "Straw Phonation"

PURPOSE

The purpose of this study was to determine the short-term effect of 2 semi-occluded vocal tract training programs, "resonant voice training using nasal consonants" versus "straw phonation," on the vocal quality of vocally healthy future occupational voice users.

METHOD

A multigroup pretest-posttest randomized control group design was used. Thirty healthy speech-language pathology students with a mean age of 19 years (range: 17-22 years) were randomly assigned into a resonant voice training group (practicing resonant exercises across 6 weeks, n = 10), a straw phonation group (practicing straw phonation across 6 weeks, n = 10), or a control group (receiving no voice training, n = 10). A voice assessment protocol consisting of both subjective (questionnaire, participant's self-report, auditory-perceptual evaluation) and objective (maximum performance task, aerodynamic assessment, voice range profile, acoustic analysis, acoustic voice quality index, dysphonia severity index) measurements and determinations was used to evaluate the participants' voice pre- and posttraining. Groups were compared over time using linear mixed models and generalized linear mixed models. Within-group effects of time were determined using post hoc pairwise comparisons.

RESULTS

No significant time × group interactions were found for any of the outcome measures, indicating no differences in evolution over time among the 3 groups. Within-group effects of time showed a significant improvement in dysphonia severity index in the resonant voice training group, and a significant improvement in the intensity range in the straw phonation group.

CONCLUSIONS

Results suggest that the semi-occluded vocal tract training programs using resonant voice training and straw phonation may have a positive impact on the vocal quality and vocal capacities of future occupational voice users. The resonant voice training caused an improved dysphonia severity index, and the straw phonation training caused an expansion of the intensity range in this population.

Validation and Evaluation of the Effects of Semi-Occluded Face Mask Straw Phonation Therapy Methods on Aerodynamic Parameters in Comparison to Traditional Methods

OBJECTIVES/HYPOTHESIS

Traditional semi-occluded vocal tract therapies have the benefit of improving vocal economy but, do not allow for connected speech during rehabilitation. In this study, we introduce a semi-occluded face mask (SOFM) as an improvement upon current methods. This novel technique allows for normal speech production, and will make the transition to everyday speech more natural. We hypothesize that use of an SOFM will lead to the same gains in vocal economy seen in traditional methods.

STUDY DESIGN

Repeated measures excised canine larynx bench experiment with each larynx subject to controls and a randomized series of experimental conditions.

METHODS

Aerodynamic data were collected for 30 excised canine larynges. The larynges were subjected to conditions including a control, two tube extensions (15 and 30 cm), and two tube diameters (6.5 and 17 mm) both with and without the SOFM. Results were compared between groups and between conditions within each group.

RESULTS

No significant differences were found between the phonation threshold pressure and phonation threshold flow measurements obtained with or without the SOFM throughout all extension and constriction levels. Significant differences in phonation threshold pressure and phonation threshold flow were observed when varying the tube diameter while the same comparison for varying the tube length at least trended toward significance.

CONCLUSIONS

This study suggests that a SOFM can be used to elicit the same gains in vocal economy as what has been seen with traditional semi-occluded vocal tract methods. Future studies should test this novel technique in human subjects to validate its use in a clinical setting.

Aerodynamic measures of glottal function: what extra can they tell us and how do they guide management?

PURPOSE OF REVIEW

This article will define the major advances in laryngeal aerodynamics research from recent evidence-based literature.

RECENT FINDINGS

Recently published research focuses on new applications of aerodynamic parameters to improve patient diagnosis and outcomes, as well as further elucidating the mechanisms of phonation using computational modeling and excised larynges.

SUMMARY

Although there is an extensive amount of research on improving the diagnosis and treatment of voice disorders using aerodynamics, the majority of recent literature lacks any conclusive evidence on new methods for use in the clinic; further research in these is needed. The best practices for resonance tube phonation in water and semi-occluded voice therapy are being investigated, as is the exact mechanism by which glottal airflow interacts with vocal folds to produce phonation. It is recommended that clinicians evaluate patients with Parkinson's disease on the basis of airflow declination and lung volume expended per syllable to avoid dependence on an acoustic signal. In addition, advances in modeling laryngeal disorders and structures will contribute to future research into treatments and diagnosis. Now that the groundwork has been laid, it is crucial to begin evaluating such techniques in patient populations.