Perceptual and Computational Estimates of Vocal Breathiness and Roughness in Sustained Phonation and Connected Speech.

OBJECTIVE: Clinical assessment of voice quality (VQ) often uses a combination of sustained phonations and more prolonged and more complex vocalizations. The purpose of this study was to compare the perceived vocal breathiness and vocal roughness of sustained phonations and connected speech over a wide range of dysphonia severity and to evaluate their relationship with acoustic measures and bioinspired models of breathiness and roughness. METHODS: VQ dimension-specific single-variable matching task (SVMT) was used to index the perceived breathiness or roughness of five male and five female talkers on the basis of a sustained /a/ phonation and the 5th CAPE-V sentence. Acoustic measures of cepstral peak, autocorrelation peak and psychoacoustic measures of pitch strength, and temporal envelope standard deviation (EnvSD) was used to predict perceived breathiness and roughness judgments obtained from 10 listeners, respectively. RESULTS: High intra- and inter-listener reliability was observed for sustained phonations and connected speech. Perceived breathiness and roughness of sustained vowels and sentences obtained using SVMT were highly correlated for most dysphonic voices. The pitch strength model of breathiness was able to capture larger amount of perceptual variance compared to cepstral peak in both vowels and sentences. Autocorrelation peak was strongly correlated to perceived roughness in sentences while EnvSD was strongly correlated to perceived roughness in vowels. CONCLUSIONS: Results provide evidence that perception of VQ via SVMT can be successfully extended to connected speech. Computational models of VQ can be easily adapted to connected speech. Such automated models of VQ perception are valuable due to their computational efficiency and their ability to accurately capture the non-linearities of the human auditory system.

Acoustic-Perceptual Correlates of Voice Among Steam Train Engineers: Effects of Noise and Hearing Protection.

Occupational voice users are at a higher risk for developing voice disorders due to their vocal demands, such as prolonged periods of work-related voice use and nonideal environmental factors, such as speaking above background noise. The current study focused on the effects of background noise and hearing protection on acoustic-perceptual correlates of voice among steam train engineers. Fourteen participants phonated vowel /a/, read a phrase, and described a map under different noise and hearing protection conditions. Relative sound pressure level, relative fundamental frequency, and perceived vocal effort and disturbance decreased in the presence of hearing protection for all noise conditions. In contrast, these acoustic measures increased in the absence of hearing protection supporting Lombard effect. Overall, results of the current study provide insight into possible risks to vocal health in workers exposed to high levels of background noise and use hearing protection.

Influence of Cognitive Load on Voice Production: A Scoping Review.

Cognitive-motor interactions in speech production have a strong theoretical basis. However, majority of the existing literature has primarily focused on subjective and objective measures related to speech and not voice. This systematic review gathered evidence on the potential relationship between cognitive load and voice production. A search of five databases, website, citation review, and author search were completed in a sequential order to find published and unpublished literature from 1992 to 2022 using a combination of search terms including voice, cognitive load/demand/effort/flexibility, dual task, and speech production/motor. Studies for which the primary dependent variables were linguistic, or speech measures were included if voice acoustics was also measured and described. A final sample of nine articles were identified as meeting inclusion criteria: completed between 1992 and 2022, healthy adults (18+), and American English speakers. The review indicated that existing literature on the influence of cognitive load on voice production is limited. Acoustic measures, such as fundamental frequency, sound pressure level, and cepstral peak prominence, do not show consistent patterns of change with an increase in cognitive load. It is likely that the inconsistencies in the speech or cognitive task type and measurement of individual reaction to cognitive load changes may have led to these varied results. Further research using a range/continuum of cognitive tasks varying in load/difficulty level and physiological measurements is warranted to understand the underlying mechanisms of behavioral performance with implications for clinical voice assessment and rehabilitation.

Evaluating the Effect of Voice Quality Covariance on Auditory-Perceptual Evaluation Using a Novel Two-Dimensional Magnitude Estimation Task.

PURPOSE: Most people with dysphonia present with voices that vary along more than one voice quality (VQ) dimension. This study sought to examine the effect of covariance between breathy and rough VQ in natural voices. METHOD: A two-dimensional matrix of 16 /a/ vowels was selected such that two VQ dimensions (breathiness and roughness) were sampled on a 4-point severity scale (none, mild, moderate, and severe). Ten listeners evaluated 480 stimuli (16 stimuli × 10 repetitions × 3 blocks) on one-dimensional magnitude estimation (1DME) tasks and a novel two-dimensional magnitude estimation (2DME) task that allowed for simultaneous measurement of breathiness and roughness. RESULTS: Data indicated high intra- and interrater reliabilities for both breathiness and roughness in the 2DME and 1DME tasks. Correlation analyses revealed a strong correlation between 2DME and 1DME judgments for breathiness and roughness (r > .95). There was also a minimal correlation between breathy and rough VQ in the 2DME task (r < .10). CONCLUSIONS: Covarying roughness or breathiness had less impact on the perception of the other VQ in natural dysphonic voices in 2DME compared to 1DME. An understanding and quantification of the perceptual interactions among the dimensions will aid in the refinement of computational models and in the establishment of the validity of clinical scales for VQ perception.

Development and Validation of a Single-Variable Comparison Stimulus for Matching Strained Voice Quality Using a Psychoacoustic Framework.

PURPOSE: Acoustic and perceptual quantification of vocal strain has been a vexing problem for years. To increase measurement rigor, a suitable single-variable matching stimulus for strain was developed and validated, based on the matching stimulus used previously for breathy and rough voice qualities. METHOD: A set of 21 comparison stimuli for a single-variable matching task (SVMT) was synthesized based on a speech-shaped sawtooth waveform mixed with speech-shaped noise. Variable bandpass filter gain in mid-to-high frequencies achieved a wide range of computed sharpness (in constant sharpness steps) and served as the independent variable for the SVMT. Ten natural /ɑ/ stimuli with a wide range of the primary voice quality of strain and a minimum of breathiness or roughness were selected and assessed using the SVMT. Natural voice samples and synthetic comparison stimuli were also assessed using a perceptual magnitude estimation (ME) task. RESULTS: ME data validated the correspondence of the set of comparison stimuli to varying perceived strain. Perceived strain magnitudes of the comparison stimuli increased significantly and linearly with computed sharpness (r 2 = .99). A linear regression revealed that strain matching values were significantly predicted by computed sharpness (r 2 = .96) and perceived strain magnitudes (r 2 = .95) of the natural voice stimuli. CONCLUSION: The perception of vocal strain is strongly associated with computed sharpness and is captured accurately and precisely using an SVMT, in which the independent variable is the bandpass filter gain (in steps of equal sharpness) applied to the comparison stimuli.

Effects of Vibratory Source on Auditory-Perceptual and Bio-Inspired Computational Measures of Pediatric Voice Quality.

OBJECTIVE: The vibratory source for voicing in children with dysphonia is classified into three categories including a glottal vibratory source (GVS) observed in those with vocal lesions or hyperfunction; supraglottal vibratory sources (SGVS) observed secondary to laryngeal airway injuries, malformations, or reconstruction surgeries; and a combination of both glottal and supraglottal vibratory sources called mixed vibratory source (MVS). This study evaluated the effects of vibratory source on three primary dimensions of voice quality (breathiness, roughness, and strain) in children with GVS, SGVS, and MVS using single-variable matching tasks and computational measures obtained from bio-inspired auditory models. METHODS: A total of 44 dysphonic voice samples from children aged 4-11 years were selected. Seven listeners rated breathiness, roughness, and strain of 1000-ms /ɑ/ samples using single-variable matching tasks. Computational estimates of pitch strength, amplitude modulation filterbank output, and sharpness were obtained through custom-designed MATLAB algorithms. RESULTS: Perceived roughness and strain were significantly higher in children with SGVS and MVS compared to children with GVS. Among the computational measures, only the modulation filterbank output resulted in significant differences among vibratory sources; a posthoc test revealed that children with SGVS had greater amplitude modulation than children with GVS, as expected from their rougher voice quality. CONCLUSIONS: The results indicate that the output of an auditory amplitude modulation filterbank model may capture characteristics of SGVS that are strongly related to the rough voice quality.

Pitch strength of normal and dysphonic voices.

Two sounds with the same pitch may vary from each other based on saliency of their pitch sensation. This perceptual attribute is called "pitch strength." The study of voice pitch strength may be important in quantifying of normal and pathological qualities. The present study investigated how pitch strength varies across normal and dysphonic voices. A set of voices (vowel /a/) selected from the Kay Elemetrics Disordered Voice Database served as the stimuli. These stimuli demonstrated a wide range of voice quality. Ten listeners judged the pitch strength of these stimuli in an anchored magnitude estimation task. On a given trial, listeners heard three different stimuli. The first stimulus represented very low pitch strength (wide-band noise), the second stimulus consisted of the target voice and the third stimulus represented very high pitch strength (pure tone). Listeners estimated pitch strength of the target voice by positioning a continuous slider labeled with values between 0 and 1, reflecting the two anchor stimuli. Results revealed that listeners can judge pitch strength reliably in dysphonic voices. Moderate to high correlations with perceptual judgments of voice quality suggest that pitch strength may contribute to voice quality judgments.

Interactions Between Breathy and Rough Voice Qualities and Their Contributions to Overall Dysphonia Severity.

PURPOSE: Dysphonic voices typically present multiple voice quality dimensions. This study investigated potential interactions between perceived breathiness and roughness and their contributions to overall dysphonia severity. METHOD: Synthetic stimuli based on four talkers were created to systematically map out potential interactions. For each talker, a stimulus matrix composed of 49 stimuli (seven breathiness steps × seven roughness steps) was created by varying aspiration noise and open quotient to manipulate breathiness and superimposing amplitude modulation of varying depths to simulate roughness. One-dimensional matching (1DMA) and magnitude estimation (1DME) tasks were used to measure perceived breathiness, roughness, their potential interactions, and overall dysphonia severity. Additional 1DME tasks were used to assess a set of natural stimuli that varied along both breathiness and roughness. RESULTS: For the synthetic stimuli, the 1DMA task indicated little interaction between the two voice qualities. For the 1DME task, breathiness magnitude was influenced by roughness step to a greater extent than roughness magnitude was influenced by breathiness step. The additive contributions of breathiness and roughness to overall severity gradually diminished with increasing breathiness and roughness steps, possibly reflecting a ceiling effect in the 1DME task. For the natural stimuli, little consistent interaction was observed between breathiness and roughness. CONCLUSIONS: The matching task revealed minimal interaction between perceived breathiness and roughness, whereas the magnitude estimation task revealed some interaction between the two qualities and their cumulative contributions to overall dysphonia severity. Task differences are discussed in terms of differences in response bias and the role of perceptual anchors. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.21313701.

Predicting Perceived Vocal Roughness Using a Bio-Inspired Computational Model of Auditory Temporal Envelope Processing.

PURPOSE: Vocal roughness is often present in many voice disorders but the assessment of roughness mainly depends on the subjective auditory-perceptual evaluation and lacks acoustic correlates. This study aimed to apply the concept of roughness in general sound quality perception to vocal roughness assessment and to characterize the relationship between vocal roughness and temporal envelop fluctuation measures obtained from an auditory model. METHOD: Ten /ɑ/ recordings with a wide range of roughness were selected from an existing database. Ten listeners rated the roughness of the recordings in a single-variable matching task. Temporal envelope fluctuations of the recordings were analyzed with an auditory processing model of amplitude modulation that utilizes a modulation filterbank of different modulation frequencies. Pitch strength and the smoothed cepstral peak prominence were also obtained for comparison. RESULTS: Individual simple regression models yielded envelope standard deviation from a modulation filter with a low center frequency (64.3 Hz) as a statistically significant predictor of vocal roughness with a strong coefficient of determination (r 2 = .80). Pitch strength and CPPS were not significant predictors of roughness. CONCLUSION: This result supports the possible utility of envelope fluctuation measures from an auditory model as objective correlates of vocal roughness.

Vocal Fatigue in Prospective Vocal Professionals.

OBJECTIVES: The goals of the study were to (a) examine vocal fatigue in speech-language pathology students through subjective and objective measures following a novel 30-minute vocal loading task (VLT) and (b) evaluate the effects of psychosocial factors on vocal fatigue. METHODS: Seventeen speech-language pathology students completed a 30-minute VLT using the LingWAVES software program. In addition to maintaining target intensity goals during reading a text, participants were also required to modify their pitch and voice quality. Vocal fatigue was measured subjectively using Vocal Fatigue Index and Borg vocal effort scale and objectively using variations of relative sound pressure level, fundamental frequency, pitch strength, smoothed cepstral peak prominence (CPPS), and acoustic voice quality index before, during, and after VLT. Participants provided information on their sleep quantity, stress, and depression through nonstandardized and standardized surveys. RESULTS: Results revealed that perceived effort and fatigue increased significantly after the 30-minute VLT. Acoustic measures of relative sound pressure level and fundamental frequency and increased systematically during and after the completion of task. All students were moderately stressed and measures related to pitch were highly related with perceived stress. CONCLUSIONS: The results of this study provide support for altering multiple vocal parameters to induce measurable changes in vocal fatigue following a short-duration VLT.

Developing Clinically Relevant Scales of Breathy and Rough Voice Quality.

The most common measurement tools used in the perceptual evaluation of voice quality yield ordinal data and thus do not support the establishment of mathematical relationships among different measurement values. This makes their interpretation challenging. Among the many desirable features of any psychophysical measurement tool is the ability to quantify the difference between two or more measurements and the ability to interpret the measurements in a manner that is related to the experience of the observer. The former allows one to compare among measurements using simple mathematics, while the latter allows that comparison to be interpreted in constructive ways. In this paper we describe the development of standard measurement scales for two dimensions of voice quality, following an approach that has been applied successfully to the perception of loudness. The scales follow step-by-step procedures used to develop the sone scale of loudness, which ties physical units to the perceptual estimates of loudness magnitude. Goals of the current work include development of analogous scales for the perception of breathy and rough voice qualities. First, the relationship between perceived voice quality and physical units were established using single-variable matching tasks. Second, the relationship between a change in physical units from the single-variable matching tasks and perceived voice quality magnitude were established using magnitude estimation tasks. Third, single reference points were identified on breathy and rough continuums. Finally, all points on the newly established voice quality continuums were rescaled relative to these arbitrary reference points. The proposed breathiness and roughness scales result in ratio-level data with standard measurement units that support quantitative comparisons of perceptual judgments. Such judgments can be used, for example, to compare magnitude of change pre- and post-treatment.

Using Pitch Height and Pitch Strength to Characterize Type 1, 2, and 3 Voice Signals.

OBJECTIVE: Classifying dysphonic voices as type 1, 2, and 3 signals based on their periodicity enables researchers to determine the validity of acoustic measures derived from them. Existing methods of signal typing are commonly performed by listening to the voice sample and visualizing them on narrow-band spectrograms that require training, time, and are subjective in nature. The current study investigated pitch-based metrics (pitch height and pitch strength) as correlates to characterizing voice signal types. The computational estimates were validated with perceptual judgments of pitch height and pitch strength. METHODS: Pitch height and pitch strength were estimated from Auditory-Sawtooth Waveform Inspired Pitch Estimator Prime algorithm for 30 dysphonic voice segments (10 per type). Ten listeners evaluated pitch height through a single-variable matching task and pitch strength through an anchored magnitude estimation task. One way analyses of variance were used to determine the effects of signal type on pitch height and pitch strength estimates. Relationship between computational and perceptual estimates was evaluated using correlation coefficients and their significance. RESULTS: There was a significant difference between signal types in both computational and perceptual pitch strength estimates. Periodic type 1 signals had greater pitch strength compared to type 2 and 3 signals. Auditory-Sawtooth Waveform Inspired Pitch Estimator Prime produced robust computational estimates of pitch height even in type 3 signals when compared to other acoustic software. Listeners were able to reliably judge pitch height in type 2 and 3 signals despite their lack of a clear fundamental frequency. CONCLUSIONS: Pitch height and pitch strength can be measured in all dysphonic voices irrespective of signal periodicity.

Perceptual and Quantitative Assessment of Dysphonia Across Vowel Categories.

OBJECTIVES: This study aims to determine the sensitivity of perceptual and computational correlates of breathy and rough voice quality (VQ) across multiple vowel categories using single-variable matching tasks (SVMTs). METHODS: Sustained phonations of /a/, /i/, and /u/ from 20 dysphonic talkers (10 with primarily breathy voices and 10 with primarily rough voices) were selected from the University of Florida Dysphonic Voice Database. For primarily breathy voices, perceived breathiness was judged, and for primarily rough voices, perceived roughness was judged by the same group of 10 listeners using an SVMT with five replicates per condition. Measures of pitch strength, cepstral peak, and autocorrelation peak were applied to models of the perceptual data. RESULTS: Intra- and inter-rater reliability were high for both the breathiness and the roughness perceptual tasks. For breathiness judgments, the effect of vowel was small. Averaged over all talkers and listeners, breathiness judgments for /a/, /i/, and /u/ were -11.6, -11.2, and -12.2 dB noise-to-signal ratio, respectively. For roughness judgments, the effect of vowel was larger. The perceived roughness of /a/ was higher than /i/ or /u/ by 3 dB modulation depth. Pitch strength was the most accurate predictor of breathiness matching (r2 = 0.84-0.94 across vowels), and log-transformed autocorrelation peak was the most accurate predictor of roughness matching (r2 = 0.59-0.83 across vowels). CONCLUSIONS: Breathiness is more consistently represented across vowels for dysphonic voices than roughness. This work represents a critical step in advancing studies of voice quality perception from single vowels to running speech.

Objective Indices of Perceived Vocal Strain.

BACKGROUND: A limited number of experiments have investigated the perception of strain compared to the voice qualities of breathiness and roughness despite its widespread occurrence in patients who have hyperfunctional voice disorders, adductor spasmodic dysphonia, and vocal fold paralysis among others. OBJECTIVE: The purpose of this study is to determine the perceptual basis of strain through identification and exploration of acoustic and psychoacoustic measures. METHODS: Twelve listeners evaluated the degree of strain for 28 dysphonic phonation samples on a five-point rating scale task. Computational estimates based on cepstrum, sharpness, and spectral moments (linear and transformed with auditory processing front-end) were correlated to the perceptual ratings. RESULTS: Perceived strain was strongly correlated with cepstral peak prominence, sharpness, and a subset of the spectral metrics. Spectral energy distribution measures from the output of an auditory processing front-end (ie, excitation pattern and specific loudness pattern) accounted for 77-79% of the model variance for strained voices in combination with the cepstral measure. CONCLUSIONS: Modeling the perception of strain using an auditory front-end prior to acoustic analysis provides better characterization of the perceptual ratings of strain, similar to our prior work on breathiness and roughness. Results also provide evidence that the sharpness model of Fastl and Zwicker (2007) is one of the strong predictors of strain perception.

The Perception of Breathiness in the Voices of Pediatric Speakers.

BACKGROUND: The perception of pediatric voice quality has been investigated using clinical protocols developed for adult voices and acoustic analyses designed to identify important physical parameters associated with normal and dysphonic pediatric voices. Laboratory investigations of adult dysphonia have included sophisticated methods, including a psychoacoustic approach that involves a single-variable matching task (SVMT), characterized by high inter- and intra-listener reliability, and analyses that include bio-inspired models of auditory perception that have provided valuable information regarding adult voice quality. OBJECTIVES: To establish the utility of a psychoacoustic approach to the investigation of voice quality perception in the context of pediatric voices? METHODS: Six listeners judged the breathiness of 20 synthetic vowel stimuli using an SVMT. To support comparisons with previous data, stimuli were modeled after four pediatric speakers and synthesized using Klatt with five parameter settings that influence the perception of breathiness. The population average breathiness judgments were modeled with acoustic measures of loudness ratio, pitch strength, and cepstral peak. RESULTS: Listeners reliably judged the perceived breathiness of pediatric voices, as with previous investigations of breathiness in adult dysphonic voices. Breathiness judgments were accurately modeled by loudness ratio (r2 = 0.93), pitch strength (r2 = 0.91), and cepstral peak (r2 = 0.82). Model accuracy was not affected significantly by including stimulus fundamental frequency and was slightly higher for pediatric than for adult voices. CONCLUSIONS: The SVMT proved robust for pediatric voices spanning a wide range of breathiness. The data indicate that this is a promising approach for future investigation of pediatric voice quality.

Speed of Pitch Change in People with Parkinson's Disease: A Pilot Study

Objective: To examine laryngeal maximum performance through a novel pitch diadochokinetic (DDK) task in people with Parkinson's disease (PD) and healthy controls. Methods: This exploratory pilot study included a total of eight people with PD (seven male and one female) and eight healthy controls. Participants were instructed to rapidly transition or alternate between a chosen comfortable low and high pitch and were instructed to complete the task as a pitch glide. An Auditory Sawtooth Waveform Inspired Pitch Estimator-Prime model was used to first extract the pitch contour and then a customized MATLAB algorithm was used to compute and derive measures of pitch range and pitch slope. Results: Pitch range and slope were reduced in some participants with PD. Effects of age and disease duration were observed in people with PD: reductions in both pitch measures with increase in age and disease duration. Conclusions: A novel pitch DDK task may supplement the conventional laryngeal DDK task in the evaluation and treatment of motor speech and voice disorders. Individual variability analysis may provide specific diagnostic and therapeutic insights for people with PD.

Objetivo: Examinar el máximo rendimiento laríngeo a través de una novedosa tarea diadococinética de tono (DDK, por sus siglas en inglés) en personas con enfermedad de Parkinson (EP) y controles sanos. Métodos: Este estudio piloto exploratorio incluyó un total de ocho personas con EP (siete hombres y una mujer) y ocho controles sanos. Se instruyó a los participantes para que hicieran una transición rápida o alternaran entre un tono bajo y uno alto que les resultara cómodo y se les indicó que completaran la tarea como un deslizamiento de tono. Se utilizó un modelo de Estimador de Tono Inspirado en la Forma de Onda de Diente de Sierra Auditiva-Prime para extraer primero el contorno del tono y luego se utilizó un algoritmo MATLAB personalizado para calcular y derivar medidas de rango de tono y pendiente de tono. Resultados: El rango y la pendiente de tono se redujeron en algunos participantes con EP. Se observaron efectos de la edad y la duración de la enfermedad en personas con EP: reducciones en ambas medidas de tono con el aumento de la edad y la duración de la enfermedad. Conclusiones: Una nueva tarea de DDK de tono podría complementar la tarea DDK laríngea convencional en la evaluación y el tratamiento de trastornos motores del habla y de la voz. El análisis de la variabilidad individual podría proporcionar información específica de diagnóstico y terapéutica para personas con EP.

Modeling of Breathy Voice Quality Using Pitch-strength Estimates.

BACKGROUND: The characteristic voice quality of a speaker conveys important linguistic, paralinguistic, and vocal health-related information. Pitch strength refers to the salience of pitch sensation in a sound and was recently reported to be strongly correlated with the magnitude of perceived breathiness based on a small number of voice stimuli. OBJECTIVE: The current study examined the relationship between perceptual judgments of breathiness and computational estimates of pitch strength based on the Aud-SWIPE (P-NP) algorithm for a large number of voice stimuli (330 synthetic and 57 natural). METHODS AND RESULTS: Similar to the earlier study, the current results confirm a strong relationship between estimated pitch strength and listener judgments of breathiness such that low pitch-strength values are associated with voices that have high perceived breathiness. Based on this result, a model was developed for the perception of breathy voice quality using a pitch-strength estimator. Regression functions derived between the pitch-strength estimates and perceptual judgments of breathiness obtained from matching task revealed a linear relationship for a subset of the natural stimuli. We then used this function to obtain predicted breathiness values for the synthetic and the remaining natural stimuli. CONCLUSIONS: Predicted breathiness values from our model were highly correlated with the perceptual data for both types of stimuli. Systematic differences between the breathiness of natural and synthetic stimuli are discussed.

Influence of Smartphones and Software on Acoustic Voice Measures.

This study assessed the within-subject variability of voice measures captured using different recording devices (i.e., smartphones and head mounted microphone) and software programs (i.e., Analysis of Dysphonia in Speech and Voice (ADSV), Multi-dimensional Voice Program (MDVP), and Praat). Correlations between the software programs that calculated the voice measures were also analyzed. Results demonstrated no significant within-subject variability across devices and software and that some of the measures were highly correlated across software programs. The study suggests that certain smartphones may be appropriate to record daily voice measures representing the effects of vocal loading within individuals. In addition, even though different algorithms are used to compute voice measures across software programs, some of the programs and measures share a similar relationship.

Listener Perception of Monopitch, Naturalness, and Intelligibility for Speakers With Parkinson's Disease.

PURPOSE: Given the potential significance of speech naturalness to functional and social rehabilitation outcomes, the objective of this study was to examine the effect of listener perceptions of monopitch on speech naturalness and intelligibility in individuals with Parkinson's disease (PD). METHOD: Two short utterances were extracted from monologue samples of 16 speakers with PD and 5 age-matched adults without PD. Sixteen listeners evaluated these stimuli for monopitch, speech naturalness and intelligibility using the visual sort and rate method. RESULTS: Naïve listeners can reliably judge monopitch, speech naturalness, and intelligibility with minimal familiarization. While monopitch and speech intelligibility were only moderately correlated, monopitch and speech naturalness were highly correlated. CONCLUSIONS: A great deal of attention is currently being paid to improvement of vocal loudness and thus speech intelligibility in PD. Our findings suggest that prosodic characteristics such as monopitch should be explored as adjuncts to this treatment of dysarthria in PD. Development of such prosodic treatments may enhance speech naturalness and thus improve quality of life.

Effect of training frequency on maximum expiratory pressure.

PURPOSE: To determine the effects of expiratory muscle strength training (EMST) frequency on maximum expiratory pressure (MEP). METHOD: We assigned 12 healthy participants to 2 groups of training frequency (3 days per week and 5 days per week). They completed a 4-week training program on an EMST trainer (Aspire Products, LLC). MEP was the primary outcome measure used to determine the effect of training frequency. RESULTS: Participants who trained 3 days per week produced equivalent amounts of improvement in MEP compared with participants who trained 5 days per week. An overall improvement in MEP over the 4-week training period indicated a 33% increase when the data was collapsed across the 2 training groups. CONCLUSION: The effects occurring with respiratory muscle strength training in healthy young adults are likely to be different from those occurring in patient populations. Therefore, the results of the present study suggest exploring the variable of training frequency in patient populations. Such knowledge will be informative for designing clinical protocols that are effective and may result in improved treatment compliance for those suffering from expiratory muscle weakness.