Relationships Between Vocal Fold Adduction Patterns, Vocal Acoustic Quality, and Vocal Effort in Individuals With and Without Hyperfunctional Voice Disorders

OBJECTIVES/HYPOTHESIS

Increased vocal effort and aberrant vocal quality are often attributed to vocal fold hyperadduction in hyperfunctional voice disorders. However, there are currently no established methods to quantify vocal fold adduction beyond subjective descriptors in this clinical population. Furthermore, relationships between vocal fold adduction patterns, vocal effort severity, and vocal quality are not well characterized. Therefore, the objectives of this study were to (1) quantify vocal fold adduction, applying a previously validated method developed for patients with vocal fold paralysis, and (2) correlate these measures with acoustic vocal quality and self-perceived measures of vocal effort severity.

METHODS

A deep learning program, Automated Glottic Action Tracking using artificial Intelligence, was used to track glottic angle configurations and vocal fold adduction velocities on laryngoscopic videos across 60 laryngoscopies (20 primary muscle tension dysphonia [pMTD], 20 phonotraumatic lesions, and 20 healthy controls). Voice samples were also acquired, and cepstral peak prominence (CPP) and H1-H2 acoustic measures were used to quantify vocal quality. Participants were also asked to rate their vocal effort on a 100 mm visual analog scale.

RESULTS

There were no significant group differences in glottic angle configurations or vocal fold adduction velocities, although there were trends toward increased peak vocal fold adduction velocities in patients with hyperfunctional voice disorders compared to controls. Vocal effort was significantly higher in the two hyperfunctional groups compared to controls. CPP was significantly lower in the pMTD group, but there were no group differences in acoustic parameters between any of the other groups or for H1-H2 values.

CONCLUSION

Despite significantly more vocal effort reported in patients with hyperfunctional voice disorders, there were no significant group differences in vocal fold adduction patterns. These findings suggest other physiologic mechanisms may also be responsible for the symptoms and genesis of pMTD and benign vocal fold lesions.

The Effects of Reading Speed on Acoustic Voice Parameters and Self-reported Vocal Fatigue in Students

INTRODUCTION

Vocal loading tasks (VLTs) help researchers gather acoustic measurements and understand how a healthy speaker adjusts their voice in response to challenges. There is a dearth of evidence measuring the impact of speaking rate in VLTs on acoustic voice parameters and vocal fatigue.

OBJECTIVES

In the present study, the relationships between acoustic voice parameters and self-reported vocal fatigue were examined through an experimental VLT.

METHODS

38 students completed a 45-minute VLT which involved the recording of three randomized reading tasks. The tasks varied by the speed in which the words were presented (slow, medium, fast) on a computer monitor. Vocal fatigue ratings were measured subjectively using a Borg scale and negative adaptations to vocal loading were measured objectively using Sound Pressure Level (SPL, in dBA), fundamental frequency (fo, in semitones), and phonation time (Dt %).

RESULTS

Analysis indicated that vocal fatigue increases with time, and the slope of this relationship is affected by the speaking rate. SPL and fo increased with speaking rate and the standard deviation of SPL and fo decreased with speaking rate. On average, the male participants' phonation time values were 7.8% lower than the female participants. The rate of increase of vocal fatigue with time during the experiment was higher in the fast speaking style compared to the slow and medium ones.

CONCLUSION

The results provide support that the novel VLT altered multiple vocal parameters to induce measurable changes in vocal fatigue.

Effects of warm-up exercises on self-assessed vocal effort

PURPOSE

An elevated sense of vocal effort due to increased vocal demand is frequently reported by patients with voice disorders. However, effects of vocal warm-up on self-assessed vocal effort have not been thoroughly examined. A recently developed version of the Borg CR-10 Scale facilitates vocal effort assessments, following different vocal warm-up tasks.

METHODS

Effects of a short (5 min) vocal warm-up on self-assessed vocal effort was evaluated using the Borg CR-10. Twenty-six vocally healthy participants (13F, 13M, mean age 22.6), in two randomised groups, underwent sessions of either reading aloud or semi-occluded vocal tract exercises (SOVTE). Vocal effort was evaluated at four times: pre to post vocal warm-up and two silence periods. Non-parametric analyses for repeated measures and calculations for within-subject standard deviation were applied in group comparisons.

RESULTS

Following vocal warm-up, vocal effort ratings were increased to a statistically significant degree in both intervention groups compared to baseline ratings. After a 5-min rest in silence following completion of the vocal warm-up, vocal effort ratings returned to baseline levels in both groups. The drop in ratings immediately post warm-up compared to 5 min later was statistically significant for the SOVTE group.

CONCLUSIONS

Five minutes of vocal warm-up caused increased self-perceived vocal effort in vocally healthy individuals. The increased sense of effort dissipated faster following warm-up for the SOVTE group. When using the Borg CR-10 scale to track vocal effort, it may be beneficial to apply experience-based anchors.

Relationships Between Laryngoscopic Analysis Metrics of Supraglottic Compression and Vocal Effort in Primary Muscle Tension Dysphonia

PURPOSE

Supraglottic compression is thought to underlie vocal effort in patients with primary muscle tension dysphonia (pMTD). However, the relationship between supraglottic compression and vocal effort in this clinical population remains unclear. Gold standard laryngoscopic assessment metrics for supraglottic compression are also lacking. The goals of this study were to identify metrics proposed in the literature that could distinguish patients diagnosed with pMTD from typical voice users and determine their relationships to the vocal effort.

METHODS

Flexible laryngeal endoscopy was performed on 50 participants (25 pMTD, 25 controls). The presence of supraglottic compression was characterized using a categorical (nominal) scale and severity was quantified on ordinal and continuous scales. The three laryngoscopic metrics were correlated with self-perceived ratings of vocal effort on a 100 mm visual analog scale.

RESULTS

Inter-rater reliability was strongest for the continuous scale (P's < 0.0001) compared to categorical (P's < 0.001) and ordinal (P's < 0.001) scales. The presence of different supraglottic compression patterns varied in both groups, and there were no significant group differences on categorical (P's > 0.05) scales. Mediolateral (M-L) supraglottic compression was significantly greater in the pMTD group (P < 0.0001), and anteroposterior (A-P) compression was significantly greater in the control group (P = 0.001) using continuous scales. There were no significant relationships between any of the three laryngoscopic metric types and vocal effort ratings (P's > 0.05), except for a significantly positive relationship between anterior-posterior compression on the ordinal scale and vocal effort in the control group (P = 0.047).

CONCLUSIONS

Continuous scales are reliable and valid for distinguishing individuals with pMTD from those without voice disorders, especially occupational voice users. M-L supraglottic compression may be a better indicator of pMTD than A-P compression. However, the poor correlation between supraglottic compression and vocal effort suggests that one may not influence the other. Future studies should focus on other mechanisms underlying vocal effort in patients with pMTD.

Physiologic Voice Rehabilitation Based on Water Resistance Therapy With Connected Speech in Subjects With Vocal Fatigue

PURPOSE

The present study aimed to assess the effectiveness of a physiologic voice therapy program based on water resistance therapy (WRT) exercises including connected speech in a group of subjects with voice complaints (vocal effort and fatigue).

METHODS

Twenty-four participants with behavioral dysphonia were randomly assigned to one of two treatment groups: (1) voice treatment with WRT plus vocal hygiene program (n = 12), and (2) vocal hygiene program only (n = 12). Laryngoscopic assessment was performed in all subjects. Before and after voice therapy, participants underwent aerodynamic and electroglottographic assessment. The Voice Handicap Index (VHI) and self-assessment of resonant voice were also performed. The treatment included six voice therapy sessions. For the experimental group, the exercises consisted of a sequence of seven phonatory tasks performed with two different voice training devices (PocketVox and MaskVox). Comparison for all variables was performed between experimental group and control group.

RESULTS

Significant differences were found for experimental group for VHI physical subscale, and self-perceived resonant voice when comparing pre-post conditions. A strong negative correlation between self-perceived resonant voice and VHI physical sub-score was also reported. No significant differences were found for instrumented variables.

CONCLUSION

Physiologic voice therapy based on WRT exercises including connected speech seems to be an effective tool to improve self-perceived voice in subjects diagnosed with voice complaints. Apparently, changes are more prone to occur in perceptual variables related with physical discomfort associate with voice production. A reduction in phonatory effort and perceptual aspects of vocal fatigue are the main improvements.

A Voice Rehabilitation Protocol With the Semioccluded Ventilation Mask in Subjects With Symptoms of Vocal Fatigue and Phonatory Effort

PURPOSE

The present study was designed to assess the efficacy of a six-session physiologic voice therapy program with the semioccluded ventilation mask (SOVM) in a group of subjects with voice complaints (vocal effort and fatigue).

METHODS

Thirty-four participants with functional dysphonia were randomly assigned to one of two treatment groups: (1) voice treatment with physiologic voice therapy plus vocal hygiene program (n = 17), and (2) vocal hygiene program only (n = 17). Laryngoscopic assessment was performed in all subjects to confirm laryngeal diagnosis. Before and after voice therapy, participants underwent aerodynamic assessment. The Voice Handicap Index (VHI), Vocal Tract Discomfort Scale (VTDS), and self-assessment of resonant voice were also performed. The treatment included six voice therapy sessions. For the experimental group, the exercises consisted of a sequence of seven phonatory tasks performed with the SOVM. Comparison for all variables was performed between experimental group and control group.

RESULTS

Statistical analysis showed significant improvements for experimental group for VHI (decrease), VTDS (decrease), and self-perception of resonant voice quality (increase). Significant decrease for experimental group was observed in subglottic pressure and phonation threshold pressure.

CONCLUSION

Physiologic voice therapy based on the SOVM with connected speech exercises seems to be an effective tool to improve voice in subjects diagnosed with voice complaints. Apparently, improvements are reflected in both subjective and objective outcomes. A reduction in phonatory effort and perceptual aspects of vocal fatigue are the main subjective improvements. A decrease in air pressure-related variables seems to be the most important objective change after voice therapy.

Clinical Characteristics and Effects of Vocal Demands in Occupational Voice Users With and Without Primary Muscle Tension Dysphonia

OBJECTIVES

The objectives of this study were to (1) compare laryngeal configuration patterns in occupational voice users with and without primary muscle tension dysphonia (pMTD), (2) characterize laryngeal configurations in relation to other clinical metrics (acoustic, perceptual), and (3) determine the effects of vocal demands (load) on these clinical parameters.

METHODS

Thirty subjects (15 pMTD, 15 control) were recruited for the study. Laryngoscopic examinations and voice samples for sustained /i/ were obtained before and after a half hour vocal load task. Subjects rated their vocal effort and discomfort before and after the vocal load. Laryngeal configurations were analyzed subjectively with dichotomous and categorical rating scales and hyper function severity quantified (endolaryngeal area outlets). Overall dysphonia severity and vocal instability of each voice sample was rated on 100mm visual analog scales and cepstral peak prominence (CPP) extracted from each voice sample.

RESULTS

Laryngeal configurations between groups or vocal load condition were not distinguishable with any of the dichotomous, categorical, or quantitative laryngeal metrics. Vocal effort and discomfort ratings were significantly higher in the pMTD group compared to the control group. Vocal load also had significant effects across groups on vocal effort and vocal tract discomfort ratings. Although CPP values fell within the normal range in both groups, CPP was significantly lower in the pMTD group at both pre-load and post-load time points. Auditory-perceptual ratings were also significantly worse in the pMTD group. Vocal load did not have a significant effect on acoustic or auditory-perceptual measures.

CONCLUSION

Similar laryngeal configurations between groups at both pre- and post-vocal load suggests classic patterns of laryngeal "hyperadduction" may occur variably in occupational voice users and may not be indicative of pMTD pathophysiology. Greater vocal effort, discomfort, instability, and perturbation within the vocal system may better define pMTD than laryngeal configuration in occupational voice users with pMTD.

Behavioral Treatment Approaches to Lowering Pitch in the Female Voice

PURPOSE

To assess the outcomes of three voice therapy treatment approaches with an emphasis on lowering speaking pitch. Transmasculine and cisgender individuals may desire to lower their speaking pitch, yet there has not been a method described in the literature to do this effectively using only behavioral techniques.

METHOD

To investigate these approaches, we enrolled 32 adult cisgender females and randomly assigned them to one of four treatment groups: vocal function exercises (VFE), resonant voice therapy (RVT), lip-rounding therapy (LRT), and a control group. Participants received individual instruction and feedback on the given exercise program, and they continued to practice daily for 4 weeks.

RESULTS

Acoustic recordings were collected before treatment, immediately after the first session, and after 4 weeks of treatment. Results showed a lower minimum pitch in the physiological range, lower speaking fundamental frequency (SFF) in reading, and lower SFF in spontaneous speech-with treatment groups performing better than the control group. Additionally, participants' self-rating of the vocal effort expended to speak in a low pitch decreased over the treatment period.

CONCLUSIONS

Each treatment approach (VFE, RVT, and LRT) was successful in lowering the speaking pitch of cisgender females. These methods would likely be useful for clients seeking to speak in a lower pitch. Future research may expand results to include clinical populations, such as transmasculine individuals.

Self-Perception of Vocal Effort in Response to Modeled Communication Demands

OBJECTIVES

The optimization of vocal effort given a response to a voice demand is a common clinical and vocal performance goal. Increases in vocal effort are often in response to communication limitations from both the interlocutors and the communication environment. This study investigates the relationship between vocal effort and vocal demands from changes and limitations imposed by the communication environment.

METHODS

Thirty-seven participants rated their vocal effort associated with a map description task in a range of communication demands. These demands included communication distance (from 1 m to 4 m), loudness goal (54 dB-66 dB), and excess background noise (53 dBA-71 dBA). The vocal effort ratings were compared across the different types and extents of vocal demand conditions.

RESULTS

As would be expected, there were significant increases in vocal effort levels from the control condition to the extremes of the distance and loudness goal vocal demands. Each increase in background noise resulted in distinct increases in vocal effort level. Participants were able to use the vocal effort scale to efficiently quantify expected increases in vocal demands.

CONCLUSIONS

Increases of vocal effort level accompany increases to vocal demands that exceed the habitual or expected communication. While voice training and vocal therapy are essential for reducing internal vocal demands, clients with a goal to reduce vocal effort should also consider external vocal demands such as communication distance and background noise.

Cognitive influences on perceived phonatory exertion using the Borg CR10

Objectives: The purpose of the present study was to examine the nature of the relationship between perceptions of vocal and mental (cognitive) effort during reading and speaking tasks.Methods: One hundred and four young, healthy adult participants were randomized into one of three groups. Each group performed a writing task meant to elicit low mental effort, high mental effort, or high mental effort followed by a period of relaxation. Participants then engaged in reading and speaking tasks, meant to elicit high (suppression of a prepotent desire to speak louder) or low (no suppression of a prepotent desire to speak louder) mental effort, and completed ratings of mental effort and vocal effort via adapted versions of the Borg CR10.Results: Findings indicate that ratings of perceived mental and vocal effort are related to one another, evidenced by strong correlations, and additional analyses reveal that mental effort might drive this relationship.Conclusions: Perceptions of vocal effort appear to mirror ratings of mental effort during tasks for which vocal activity is relatively stable but cognitive demands fluctuate. The possibility that perceptions of mental effort might influence perceptions of vocal effort should be considered when creating reliable and valid measures of vocal effort as well as when interpreting currently adapted measures of vocal effort in the clinical context.

Acoustic correlates of vocal effort: External factors and personality traits

OBJECTIVES

To develop an experimental protocol to study the vocal effort generated by introducing barriers to communication, and its relationship with certain personality traits.

MATERIAL AND METHODS

The experimental protocol consisted of an interactive game in which the subject gave an investigator instructions to adopt various body positions (semi-directed communication situation). The Control situation included no constraints on communication. Then a Distance Constraint (increased distance between subject and investigator) and a Time Constraint (generation of performance stress by putting the subject in competition with others) were introduced. The vocal parameters studied comprised vocal intensity and fundamental frequency in the middle of the vowel of 3 target phonemes. Subjects also took the NEO FFI-R personality test.

RESULTS

The study included 41 women aged between 18 and 52 years. Vocal intensity and fundamental frequency increased significantly with the introduction of the constraints (P<0.05), intensity passing from 75.5dB to 81.8dB and frequency from 249.4Hz to 335.8Hz. No correlations were found between these changes and results for the various personality traits.

CONCLUSIONS

This ecological protocol enables the impact of both physical and emotional obstacles to communication to be studied. No correlations between vocal effort and personality traits emerged. A larger-scale study would be necessary to analyze the continuum between vocal effort and vocal forcing, to improve speech therapy for dysfunctional dysphonia.

Vocal Dose in Older Adults with Presbyphonia: An Analytic, Cross-Sectional Study

PURPOSE

Older patients with age-related voice changes (presbyphonia) are considered vocal under-doers due to a reportedly low a amount and intensity of voice use (ie, low vocal dose). This low voice use may be consequential to negative effects of presbyphonia like throat discomfort, as well as anxiety and frustration from difficulty communicating. Causally speaking, vocal fold atrophy (presbylaryngis) may indicate inadequate intrinsic laryngeal muscle loading with low voice use, though research is lacking. As a first step, this study examined voice use objectively using vocal dosimetry in older adults with presbyphonia. We hypothesized participants, especially if retired, would exhibit low vocal doses, and lower than reported for other populations.

METHOD

This research used an analytic, cross-sectional design with subgroup analyses to determine feasibility of vocal dosimetry in older adults with presbyphonia. Thirteen older adults with presbyphonia (7 males) completed vocal dose monitoring using an ambulatory phonation monitor (APM). The APM measured vocal parameters over a day of monitoring, from which time, cycle, and distance doses were calculated. Data also were gathered on demographics, vocal handicap, and vocal effort.

RESULTS

Descriptively, the group showed a low mean time dose as compared to published vocal dose data from other populations. Females exhibited significantly higher mean values of time dose, cycle dose, and fundamental frequency than males. Time dose for males was negatively correlated with vocal effort. Subgroup analyses failed to detect an effect of age group, but found significantly a higher mean value for time dose in employed, compared to retired, participants.

CONCLUSIONS

Consistent with self-report, we found older adults with presbyphonia exhibit low time doses, which were in contrast to high vocal doses published on teachers, patients with dysphonia, and even office workers. We found differences in vocal dose as a function of sex and employment status. Though a limited sample, findings suggest patients with presbyphonia may demonstrate low vocal dose, which may be a useful target in treatment.

Estimating Vocal Effort from the Aerodynamics of Labial Fricatives: A Feasibility Study

OBJECTIVE AND HYPOTHESIS

Vocal effort in loud voice is produced with increased subglottal pressure during vowels and increased supraglottal pressure during consonants. In the paper, our main objective is to check whether it was supported by a parallel increase in the airflow resistance of the laryngeal articulator and of the supralaryngeal articulator, here the lips.

STUDY DESIGN AND METHOD

For this comparison, our choice fell on the fricative consonants, as their production allows perfectly synchronous air pressure and airflow measurements. Also, the calculation of the real instantaneous aerodynamic resistance is possible with fricatives-as it is with vowels-whereas it is not possible with plosives. The present feasibility study on a healthy subject is based on direct subglottal and intraoral pressures and airflow measured for /f/ or /v/ and from the contiguous vowel produced in VCVCV nonsense words at different levels of intensity.

RESULTS AND CONCLUSION

The results support that the airflow resistances at the lips and that at the larynx are quite parallel. The airflow resistance at the lips during labial fricative production could provide a good picture of the laryngeal resistance during the production of continuous speech. This suggests clinical applications using both noninvasive inferred measurements of subglottal pressure variation and direct noninferred airflow measurements from more natural speech production tasks.

Behavioral, physiological and morphological correlates of parasite intensity in the wild Cururu toad (Rhinella icterica)

Large numbers of parasites are found in various organs of anuran amphibians, with parasite intensities thought to modulate the host's Darwinian fitness traits. Interaction between the anuran hosts and their multiple parasites should modulate the host's phenotypic characteristic, such as those associated with high energetic demand (such as calling effort and locomotor performance), energy balance (standard metabolic rate), and morphological plasticity (as indicated by organ masses). The present study investigated the impact of parasite intensities on the behavioral, physiological, and morphological traits of wild adult male Rhinella icterica (Anura: Bufonidae). We tested as to whether individuals with higher parasite intensities would present: 1) lower vocal calling effort in the field, as well as poorer locomotor performance and body-condition index; and 2) higher standard metabolic rates and internal organ masses. Measurements included: calling effort in the field; standard metabolic rate; locomotor performance; parasite intensity; internal organ masses (heart, liver, kidneys, intestines, stomach, lungs, hind limb muscle, and spleen); and the body-condition index. Results showed a negative association of parasite intensities with locomotor performance, and standard metabolic rate of R. icterica. A positive association between parasite intensities and relative organ masses (heart, intestines and kidneys) was also evident. Toads with higher pulmonary and intestinal parasites intensities also showed higher total parasite intensities.

Using the Borg CR10 Physical Exertion Scale to Measure Patient-perceived Vocal Effort Pre and Post Treatment

OBJECTIVES

Reduction of vocal effort is a therapeutic goal in resonant voice therapy and in the treatment of a variety of voice disorders. The Borg CR10 is a perceived effort scale that is widely accepted across a wide variety of disciplines. The purpose of the present study was to examine (1) the utility of an anchored, adapted Borg CR10 in observing treatment-related vocal effort reduction and (2) the convergent validity of the Borg CR10 in its relation to Voice Handicap Index (VHI) item 14.

STUDY DESIGN

This is a pretest-posttest experimental design.

METHODS

A total of 36 individuals with phonotraumatic hyperfunctional voice disorders completed item 14 of the VHI and the Borg CR10 at the start and completion of four sessions of resonant voice therapy treatment.

RESULTS

Scores from the Borg CR10 significantly differentiated pre- from post-therapy perceived effort levels. Convergent validity was demonstrated through significant associations with scores from item 14 of the VHI.

CONCLUSION

The anchored Borg CR10 is an easy to use clinical tool to capture treatment-related vocal effort reduction. Whereas VHI item 14 indicates how frequently increased perceived effort is experienced, the Borg CR10 captures the severity of perceived effort used. Thus, the two measures complement each other.

Speech Adjustments for Room Acoustics and Their Effects on Vocal Effort

OBJECTIVES

The aims of the present study are (1) to analyze the effects of the acoustical environment and the voice style on time dose (D_{t_p}) and fundamental frequency (mean f₀ and standard deviation std_f₀) while taking into account the effect of short-term vocal fatigue and (2) to predict the self-reported vocal effort from the voice acoustical parameters.

METHODS

Ten male and ten female subjects were recorded while reading a text in normal and loud styles, in three rooms-anechoic, semi-reverberant, and reverberant-with and without acrylic glass panels 0.5 m from the mouth, which increased external auditory feedback. Subjects quantified how much effort was required to speak in each condition on a visual analogue scale after each task.

RESULTS

(Aim1) In the loud style, D_{t_p}, f₀, and std_f₀ increased. The D_{t_p} was higher in the reverberant room compared to the other two rooms. Both genders tended to increase f₀ in less reverberant environments, whereas a more monotonous speech was produced in rooms with greater reverberation. All three voice parameters increased with short-term vocal fatigue. (Aim2) A model of the vocal effort to acoustic vocal parameters is proposed. The sound pressure level contributed to 66% of the variance explained by the model, followed by the f₀ (30%) and the modulation in amplitude (4%).

CONCLUSIONS

The results provide insight into how voice acoustical parameters can predict vocal effort. In particular, it increased when SPL and f₀ increased and when the amplitude voice modulation decreased.

An Oral Pressure Conversion Ratio as a Predictor of Vocal Efficiency

Voice production is an inefficient process in terms of energy expended versus acoustic energy produced. A traditional efficiency measure, glottal efficiency, relates acoustic power radiated from the mouth to aerodynamic power produced in the trachea. This efficiency ranges between 0.0001% and 1.0%. It involves lung pressure and hence would appear to be a useful effort measure for a given acoustic output. Difficulty in the combined measurement of lung pressure and tracheal airflow, however, has impeded clinical application of glottal efficiency. This article uses the large data base from Schutte (1980) and a few new measurements to validate a pressure conversion ratio (PCR) as a substitute for glottal efficiency. PCR has the potential for wide application because of low cost and ease of use in clinics and vocal studios.

Vocal performance affects metabolic rate in dolphins: implications for animals communicating in noisy environments

Many animals produce louder, longer or more repetitious vocalizations to compensate for increases in environmental noise. Biological costs of increased vocal effort in response to noise, including energetic costs, remain empirically undefined in many taxa, particularly in marine mammals that rely on sound for fundamental biological functions in increasingly noisy habitats. For this investigation, we tested the hypothesis that an increase in vocal effort would result in an energetic cost to the signaler by experimentally measuring oxygen consumption during rest and a 2 min vocal period in dolphins that were trained to vary vocal loudness across trials. Vocal effort was quantified as the total acoustic energy of sounds produced. Metabolic rates during the vocal period were, on average, 1.2 and 1.5 times resting metabolic rate (RMR) in dolphin A and B, respectively. As vocal effort increased, we found that there was a significant increase in metabolic rate over RMR during the 2 min following sound production in both dolphins, and in total oxygen consumption (metabolic cost of sound production plus recovery costs) in the dolphin that showed a wider range of vocal effort across trials. Increases in vocal effort, as a consequence of increases in vocal amplitude, repetition rate and/or duration, are consistent with behavioral responses to noise in free-ranging animals. Here, we empirically demonstrate for the first time in a marine mammal, that these vocal modifications can have an energetic impact at the individual level and, importantly, these data provide a mechanistic foundation for evaluating biological consequences of vocal modification in noise-polluted habitats.

Aerodynamic and acoustic features of vocal effort

OBJECTIVES

The purpose of this study was to determine the aerodynamic and acoustic features of speech produced at comfortable, maximal and minimal levels of vocal effort.

STUDY DESIGN

Prospective, quasi-experimental research design.

METHOD

Eighteen healthy participants with normal voice were included in this study. After task training, participants produced repeated syllable combinations at comfortable, maximal and minimal levels of vocal effort. A pneumotachometer and vented (Rothenberg) mask were used to record aerodynamic data, with simultaneous recording of the acoustic signal for subsequent analysis. Aerodynamic measures of subglottal pressure, translaryngeal airflow, maximum flow declination rate (MFDR), and laryngeal resistance were analyzed, along with acoustic measures of cepstral peak prominence (CPP) and its standard deviation (SD).

RESULTS

Participants produced significantly greater subglottal pressure, translaryngeal airflow, and MFDR during maximal effort speech as compared with comfortable vocal effort. When producing speech at minimal vocal effort, participants lowered subglottal pressure, MFDR, and laryngeal resistance. Acoustic changes associated with changes in vocal effort included significantly higher CPP during maximal effort speech and significantly lower CPP SD during minimal effort speech, when each was compared with comfortable effort.

CONCLUSIONS

For healthy speakers without voice disorders, subglottal pressure, translaryngeal airflow, and MFDR may be important factors that contribute to an increased sense of vocal effort. Changes in the cepstral signal also occur under conditions of increased or decreased vocal effort relative to comfortable effort.

Perceived vocal fatigue and effort in relation to laryngeal functional measures in paresis patients

OBJECTIVES/HYPOTHESIS

To determine if differences in objective measures of laryngeal function can meaningfully explain different levels of self-perceptions of effort or fatigue in patients with vocal fold paresis.

STUDY DESIGN

A retrospective chart review of 72 patients with vocal fold paresis diagnosed using laryngeal electromyography, who had either been observed (n=21), treated only by injection (n=24), or treated only by surgery (n=27).

METHODS

Before and after treatment/observation, patients' subjective ratings of severity of vocal effort and fatigue were assessed using the Glottal Function Index. Laryngeal function was assessed using maximum phonation time and translaryngeal flow.

RESULTS

None of the variables demonstrated a significant linear change across time. Post hoc Tukey analyses following analysis of variance (ANOVA) found significant differences in flow among three groups, those rating symptoms of effort as no problem, moderate problem, or severe problem. Post hoc Tukey analyses following ANOVA found significant differences in the amount that flow changed among three groups, those demonstrating no difference, minor differences, or major differences in ratings of effort before and after treatment.

CONCLUSIONS

Changes in reported symptom severity of effort were related to changes in translaryngeal midvowel flow that were not explained by passage of time.

LEVEL OF EVIDENCE

4.