The effects of divided attention on speech motor, verbal fluency, and manual task performance

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five databases, website, citation review, and author search were completed in a sequential order to find published and unpublished literature from 1992 to 2022 using a combination of search terms including voice, cognitive load/demand/effort/flexibility, dual task, and speech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.

Transcranial Direct-Current Stimulation Improves Verbal Fluency in Children with Attention Deficit Hyperactivity Disorder (ADHD)

Individuals with attention deficit hyperactivity disorder (ADHD) struggle with impaired verbal fluency as an executive function. The left and right dorsolateral prefrontal cortex (dlPFC) and the right inferior frontal gurus (IFG), which show reduced functionality in individuals with ADHD, are involved in verbal fluency. In this study, a total of thirty-seven children with ADHD participated in two separate experiments. Each experiment included three different stimulation conditions: anodal left dlPFC/cathodal right vmPFC stimulation, the reversed montage, and a sham stimulation in Experiment 1, and anodal right dlPFC, anodal right IFG with extracranial return electrode, and a sham stimulation in Experiment 2. During each session, participants performed semantic and phonemic verbal fluency tasks while receiving tDCS. The results revealed a significant main effect of stimulation condition on phonemic verbal fluency during anodal left dlPFC stimulation in Experiment 1, and on semantic verbal fluency during both real stimulation conditions in Experiment 2. In conclusion, this study suggests that anodal left dlPFC stimulation improves phonemic verbal fluency, while anodal right dlPFC and right IFG stimulation enhance semantic verbal fluency. This domain-specific improvement can be attributed to the distinct cognitive demands of phonemic and semantic verbal fluency tasks. Phonemic verbal fluency heavily relies on working memory processes, whereas semantic verbal fluency requires effective inhibitory control and cognitive flexibility.

Quantifying Spatial and Temporal Variability of Clear and Loud Speech Produced While Performing a Concurrent Visuomotor Task

PURPOSE

The purpose of this research note was to quantify the impact of concurrent performance of an attention-demanding secondary task on utterance-to-utterance movement variability associated with higher effort speaking styles, namely, clear and loud speech.

METHOD

Lip and jaw kinematics collected as part of a prior study were analyzed. Participants repeated "Buy Bobby a puppy" using habitual, loud, and clear speech styles in isolation and while performing a secondary tracking task. The lip aperture (LA) signal was segmented based on opening and closing gestures associated with the utterance. The standard deviation of each segment duration was calculated to quantify temporal variability. To quantify spatial variability, each segment was first time normalized. The mean standard deviation of the overlapping time-normalized LA amplitudes was computed for each segment from the repetitions produced in each speech style and condition (speaking in isolation vs. speaking while tracking). A relative measure of spatial variation was also computed to account for the potential impact of articulatory scaling.

RESULTS

Clear speech was associated with greater temporal and spatial variability than the habitual and loud styles. In the habitual style, talkers also exhibited a slight reduction in absolute spatial variability when speaking while tracking compared to speaking in isolation. The reduction in absolute spatial variability was likely associated with the concomitant reduction in LA range of motion, as there was no change in the relative spatial variability between conditions.

CONCLUSION

The current investigation expands prior work by quantifying spatial and temporal characteristics of different speaking styles performed in isolation and while concurrently performing an attention-demanding visuomotor task.

The efficacy of memory load on speech-based detection of Alzheimer's disease

Introduction

The study aims to test whether an increase in memory load could improve the efficacy in detection of Alzheimer's disease and prediction of the Mini-Mental State Examination (MMSE) score.

Methods

Speech from 45 mild-to-moderate Alzheimer's disease patients and 44 healthy older adults were collected using three speech tasks with varying memory loads. We investigated and compared speech characteristics of Alzheimer's disease across speech tasks to examine the effect of memory load on speech characteristics. Finally, we built Alzheimer's disease classification models and MMSE prediction models to assess the diagnostic value of speech tasks.

Results

The speech characteristics of Alzheimer's disease in pitch, loudness, and speech rate were observed and the high-memory-load task intensified such characteristics. The high-memory-load task outperformed in AD classification with an accuracy of 81.4% and MMSE prediction with a mean absolute error of 4.62.

Discussion

The high-memory-load recall task is an effective method for speech-based Alzheimer's disease detection.

Acoustic Measures of Voice and Physiologic Measures of Autonomic Arousal During Speech as a Function of Cognitive Load in Older Adults

OBJECTIVES/HYPOTHESIS

The purpose of this study was to determine the relationships among cognitive loading, autonomic arousal, and acoustic measures of voice in healthy older adults.

STUDY DESIGN

Prospective and observational.

METHODS

Twelve healthy older adults (six females) produced a sentence containing an embedded Stroop task in each of two cognitive load conditions: congruent and incongruent. Three physiologic measures of autonomic arousal (pulse volume amplitude, pulse period, and skin conductance response amplitude) and four acoustic measures of voice (cepstral peak prominence, low-to-high spectral energy ratio, fundamental frequency, and sound pressure level) were analyzed in each cognitive load condition.

RESULTS

A logistic regression model was used to predict the cognitive load condition using participant as a categorical predictor and the four acoustic measures and three autonomic measures as continuous predictors. Skin conductance response amplitude and pulse volume amplitude were both predictive of cognitive load; however, no acoustic measures of voice were statistically significant predictors of cognitive load for older adults.

CONCLUSIONS

These findings support the idea that increased cognitive load is associated with increased autonomic nervous system activity in older adults. The lack of changes in acoustic measures of voice with increased cognitive load may result from age-related changes in vocal quality and speech subsystems.

Dual-task decrements in mono-, bi- and multilingual participants: Evidence for multilingual advantage

Evidence suggests that language processing in bilinguals is less left-lateralized than in monolinguals. We explored dual-task decrement (DTD) for mono-, bi- and multilinguals in a verbal-motor dual-task paradigm. We expected monolinguals to show greater DTD than bilingual participants, who would show greater DTD than multilingual participants. Fifty right-handed participants (18 monolingual, 16 bilingual, 16 multilingual) completed verbal fluency and manual motor tasks in isolation and concurrently. Tasks were completed twice in isolation (left-handed, right-handed) and twice as dual-tasks (left-handed, right-handed); participants' motor-executing hands served proxy for hemispheric activation. Results supported the hypotheses. Completing dual-tasks incurred greater cost for manual motor tasks than for verbal fluency tasks. Negative cost of performing dual-tasks diminished as number of languages spoken increased; in fact, multilingual individuals demonstrated a dual-task advantage in both tasks when using the right hand, strongest in the verbal task. Dual-tasking had the greatest negative impact on verbal fluency of monolingual participants when the motor task was completed with the right hand; for bi- and multi-lingual participants, the greatest negative impact on verbal fluency was seen when the motor task was completed with the left hand. Results provide support for the bi-lateralization of language function in bi- and multilingual individuals.

Tracking the Costs of Clear and Loud Speech: Interactions Between Speech Motor Control and Concurrent Visuomotor Tracking

Purpose Prior work has demonstrated that competing tasks impact habitual speech production. The purpose of this investigation was to quantify the extent to which clear and loud speech are affected by concurrent performance of an attention-demanding task. Method Speech kinematics and acoustics were collected while participants spoke using habitual, loud, and clear speech styles. The styles were performed in isolation and while performing a secondary tracking task. Results Compared to the habitual style, speakers exhibited expected increases in lip aperture range of motion and speech intensity for the clear and loud styles. During concurrent visuomotor tracking, there was a decrease in lip aperture range of motion and speech intensity for the habitual style. Tracking performance during habitual speech did not differ from single-task tracking. For loud and clear speech, speakers retained the gains in speech intensity and range of motion, respectively, while concurrently tracking. A reduction in tracking performance was observed during concurrent loud and clear speech, compared to tracking alone. Conclusions These data suggest that loud and clear speech may help to mitigate motor interference associated with concurrent performance of an attention-demanding task. Additionally, reductions in tracking accuracy observed during concurrent loud and clear speech may suggest that these higher effort speaking styles require greater attentional resources than habitual speech.

Speech Performance among Healthy Malay Female Speakers during Dual Tasks and Sentence Complexity

OBJECTIVES

This study aimed to identify how different dual tasks influence speech performance among young Malay speakers by manipulating the complexity of sentences. Fifteen female speakers (20-30 years old) were audio recorded while executing a series of simple and complex sentence repetition tasks.

METHODS

Hierarchical linear modeling was conducted to examine the effects of task (speech task only, speech + cognitive tasks, speech + linguistic tasks, and speech + manual tasks) and sentence complexity (simple vs. complex), as well as their interaction on 3 outcome measures (word accuracy rate [WAR], response reaction time [RRT], and duration of sentence [DoS]).

RESULTS

Significantly higher WAR were found when participants read the sentences only compared to when they completed another task simultaneously. The pairwise comparison further revealed that the conditions of speech + manual tasks produced the lowest WAR. For RRT, participants responded significantly faster when they only read the sentences (mean = 1.36, SE = 0.17) than when they read the sentences and conducted another task at the same time (mean = 1.66, SE = 0.14; p < 0.0001). A pairwise comparison showed that the conditions of speech + manual tasks produced the longest DoS. Neither the effect of sentence complexity nor the interaction between task and sentence complexity was statistically significant across WAR, RRT, and DoS.

CONCLUSIONS

The results augment what is known about interference between speech and other concurrent tasks and provides evidence that divided attention affects manual task performance more than other tasks. In addition, sentence complexity did not affect speech performance in healthy adults. This paradigm could be used in future studies to serve as a clinical marker that can potentially distinguish mild cognitive impairment from normal aging.

Dual-task speech performance in multiple sclerosis

BACKGROUND

Although extant dual-task studies suggest cognitive-motor interference may magnify existing non-speech motor impairments in multiple sclerosis (MS), cognitive-speech motor interference in MS has not been studied. This study evaluated the presence of cognitive-speech motor interference in MS and explored within subject differences in speech measures from the single-to dual-task condition for individuals with MS with co-occurring dysarthria and impaired cognition.

METHODS

In this dual-task study, 21 individuals with MS and 21 controls read aloud a sentence (single-task) and completed a cognitive-linguistic task while simultaneously reading aloud a sentence (dual-task). Speech measures included speech and articulation rate, silent pause frequency and duration, and total sentence duration.

RESULTS

Both groups had significantly slower speech in the dual-task condition. Relative to participants with dysarthria, speech rate and sentence duration difference scores approached significance or were significantly greater for participants with MS with dysarthria and cognitive impairment. These difference scores were associated with executive function and processing speed deficits and fewer years of education.

CONCLUSION

Significant negative compounding effects for speech rate and sentence duration suggest that the dual-task paradigm shows promise for identifying individuals with MS with cognitive impairment and dysarthria at increased risk of problems with effective communication. Further research is warranted to replicate this work and evaluate the consequences of these speech aberrancies on communication effectiveness that ultimately may affect employment, social relationships, and quality of life.

Practice Mediates Bidirectional Dual-Task Interference When Performing a Novel Sequential Nonword Repetition Task

Introduction The current study examined the extent to which practice amount mediates dual-task interference patterns associated with concurrent performance of a novel speech task and attention-demanding visuomotor task. Method A Sequential Nonword Repetition Task was used to examine the effect of practice on interference associated with concurrent performance of a Visuomotor Pursuit Task. Twenty-five young adult participants were assigned to either an Extended Practice Group or a Limited Practice Group and performed a novel Sequential Nonword Repetition Task in isolation and while performing a concurrent visuomotor pursuit rotor task. Results Participants in the Limited Practice Group who were afforded a limited amount of practice exhibited dual-task interference (i.e., dual-task performance reductions) for both the speech and visuomotor tasks (i.e., bidirectional dual-task interference). Conversely, participants in the Extended Practice Group who were afforded extended practice exhibited little-to-no observable dual-task interference on the nonword repetition task. Conclusion Data from the current investigation suggest that the amount of initial practice mediates the degree of dual-task interference observed when a novel speech production task is performed with an attention-demanding Visuomotor Pursuit Task. Supplemental Material https://doi.org/10.23641/asha.14608071.

Effects of Concurrent Manual Task Performance on Connected Speech Acoustics in Individuals With Parkinson Disease

Purpose Prior investigations suggest that simultaneous performance of more than 1 motor-oriented task may exacerbate speech motor deficits in individuals with Parkinson disease (PD). The purpose of the current investigation was to examine the extent to which performing a low-demand manual task affected the connected speech in individuals with and without PD. Method Individuals with PD and neurologically healthy controls performed speech tasks (reading and extemporaneous speech tasks) and an oscillatory manual task (a counterclockwise circle-drawing task) in isolation (single-task condition) and concurrently (dual-task condition). Results Relative to speech task performance, no changes in speech acoustics were observed for either group when the low-demand motor task was performed with the concurrent reading tasks. Speakers with PD exhibited a significant decrease in pause duration between the single-task (speech only) and dual-task conditions for the extemporaneous speech task, whereas control participants did not exhibit changes in any speech production variable between the single- and dual-task conditions. Conclusions Overall, there were little to no changes in speech production when a low-demand oscillatory motor task was performed with concurrent reading. For the extemporaneous task, however, individuals with PD exhibited significant changes when the speech and manual tasks were performed concurrently, a pattern that was not observed for control speakers. Supplemental Material https://doi.org/10.23641/asha.8637008.

Bidirectional Interference Between Simulated Driving and Speaking

Purpose This study relied on acoustic measures of connected speech and several indices of driving performance to quantify interference between speaking and simulated driving. Method Three groups of 20 younger (ages 20-30 years), middle-age (ages 40-50 years), and older (ages 60-71 years) adults produced monologues and completed a simulated driving task, which involved maintaining a constant speed and lane position on a freeway. Both tasks were completed separately and concurrently. Results There were significant divided attention effects, with a reduced speaking time ratio, and increases in vocal intensity, speed variability, and steering wheel adjustments. There was a significant between-subjects age effect for intensity and fundamental frequency as the younger group had less variation with these variables compared to the other age groups across conditions. There was a significant between-subjects age effect for lane position, steering wheel position, and speed as the younger group had less variation in lane position compared to the other 2 groups, and the older group had more variation in speed and steering wheel position compared to the other 2 groups across the experimental conditions. Conclusion These findings reveal that divided attention conditions can impact both speech and simulated driving performance. The results also shed some light on the effects of age on speech and driving tasks, although the degree of interference from divided attention did not differ by age.

Cognitive Load Affects Speech Motor Performance Differently in Older and Younger Adults

Purpose The aim of this study was to determine the impact of cognitive load imposed by a speech production task on the speech motor performance of healthy older and younger adults. Response inhibition, selective attention, and working memory were the primary cognitive processes of interest. Method Twelve healthy older and 12 healthy younger adults produced multiple repetitions of 4 sentences containing an embedded Stroop task in 2 cognitive load conditions: congruent and incongruent. The incongruent condition, which required participants to suppress orthographic information to say the font colors in which color words were written, represented an increase in cognitive load relative to the congruent condition in which word text and font color matched. Kinematic measures of articulatory coordination variability and movement duration as well as a behavioral measure of sentence production accuracy were compared between groups and conditions and across 3 sentence segments (pre-, during-, and post-Stroop). Results Increased cognitive load in the incongruent condition was associated with increased articulatory coordination variability and movement duration, compared to the congruent Stroop condition, for both age groups. Overall, the effect of increased cognitive load was greater for older adults than younger adults and was greatest in the portion of the sentence in which cognitive load was manipulated (during-Stroop), followed by the pre-Stroop segment. Sentence production accuracy was reduced for older adults in the incongruent condition. Conclusions Increased cognitive load involving response inhibition, selective attention, and working memory processes within a speech production task disrupted both the stability and timing with which speech was produced by both age groups. Older adults' speech motor performance may have been more affected due to age-related changes in cognitive and motoric functions that result in altered motor cognition.

Hear speech, change your reach: changes in the left-hand grasp-to-eat action during speech processing

Research has shown that the kinematic characteristics of right-hand movements change when executed during both speech production and processing. Despite the variety of prehension and manual actions used to examine this relationship, the literature has yet to examine potential movement effects using an action with a distinct kinematic signature: the hand-to-mouth (grasp-to-eat) action. In this study, participants performed grasp-to-eat and grasp-to-place actions in (a) a quiet environment and (b) while processing speech. Results during the quiet condition replicated the previous findings; consistently smaller grasp-to-eat (compared to grasp-to-place), maximum grip apertures appeared only when using the right hand. Interestingly, in the listen condition, smaller maximum grip apertures in the grasp-to-eat movement appeared in both the right and left hands, despite the fact that participants were right-handed. This paper addresses these results in relation with similar behaviour observed in children, and discusses implications for functional lateralization and neural organization.

Rhythmic performance in hypokinetic dysarthria: Relationship between reading, spontaneous speech and diadochokinetic tasks

•We investigated speech rhythm in people with Parkinson’s Disease (PwPD) and controls. •Even mildly affected PwPD differed from controls in their rhythmic performance. •PwPD showed less difference between reading and spontaneous speech. •Spontaneous speech highlighted more differences between speakers than reading. •DDK performance did not relate to rhythmic behaviour in connected speech.

Speech Motor Sequence Learning: Effect of Parkinson Disease and Normal Aging on Dual-Task Performance

PURPOSE

Everyday communication is carried out concurrently with other tasks. Therefore, determining how dual tasks interfere with newly learned speech motor skills can offer insight into the cognitive mechanisms underlying speech motor learning in Parkinson disease (PD). The current investigation examines a recently learned speech motor sequence under dual-task conditions.

METHOD

A previously learned sequence of 6 monosyllabic nonwords was examined using a dual-task paradigm. Participants repeated the sequence while concurrently performing a visuomotor task, and performance on both tasks was measured in single- and dual-task conditions.

RESULTS

The younger adult group exhibited little to no dual-task interference on the accuracy and duration of the sequence. The older adult group exhibited variability in dual-task costs, with the group as a whole exhibiting an intermediate, though significant, amount of dual-task interference. The PD group exhibited the largest degree of bidirectional dual-task interference among all the groups.

CONCLUSIONS

These data suggest that PD affects the later stages of speech motor learning, as the dual-task condition interfered with production of the recently learned sequence beyond the effect of normal aging. Because the basal ganglia is critical for the later stages of motor sequence learning, the observed deficits may result from the underlying neural dysfunction associated with PD.

Spatiotemporal movement variability in ALS: Speaking rate effects on tongue, lower lip, and jaw motor control

PURPOSE

Although it is frequently presumed that bulbar muscle degeneration in Amyotrophic Lateral Sclerosis (ALS) is associated with progressive loss of speech motor control, empirical evidence is limited. Furthermore, because speaking rate slows with disease progression and rate manipulations are used to improve intelligibility in ALS, this study sought to (i) determine between and within-group differences in articulatory motor control as a result of speaking rate changes and (ii) identify the strength of association between articulatory motor control and speech impairment severity.

METHOD

Ten talkers with ALS and 11 healthy controls repeated the target sentence at habitual, fast, and slow rates. The spatiotemporal variability index (STI) was calculated to determine tongue, lower lip, and jaw movement variability.

RESULTS

During habitual speech, talkers with mild-moderate dysarthria displayed significantly lower tongue and lip movement variability whereas those with severe dysarthria showed greater variability compared to controls. Within-group rate effects were significant only for talkers with ALS. Specifically, lip and tongue movement variability significantly increased during slow speech relative to habitual and fast speech. Finally, preliminary associations between speech impairment severity and movement variability were moderate to strong in talkers with ALS.

CONCLUSION

Between-group differences for habitual speech and within-group effects for slow speech replicated previous findings for lower lip and jaw movements. Preliminary findings of moderate to strong associations between speech impairment severity and STI suggest that articulatory variability may vary from pathologically low (possibly indicating articulatory compensation) to pathologically high variability (possibly indicating loss of control) with dysarthria progression in ALS.

Acoustic Measures of Voice and Physiologic Measures of Autonomic Arousal during Speech as a Function of Cognitive Load

OBJECTIVES/HYPOTHESIS

This study aimed to determine the relationship among cognitive load condition and measures of autonomic arousal and voice production in healthy adults.

STUDY DESIGN

A prospective study design was conducted.

METHODS

Sixteen healthy young adults (eight men, eight women) produced a sentence containing an embedded Stroop task in each of two cognitive load conditions: congruent and incongruent. In both conditions, participants said the font color of the color words instead of the word text. In the incongruent condition, font color differed from the word text, creating an increase in cognitive load relative to the congruent condition in which font color and word text matched. Three physiologic measures of autonomic arousal (pulse volume amplitude, pulse period, and skin conductance response amplitude) and four acoustic measures of voice (sound pressure level, fundamental frequency, cepstral peak prominence, and low-to-high spectral energy ratio) were analyzed for eight sentence productions in each cognitive load condition per participant.

RESULTS

A logistic regression model was constructed to predict the cognitive load condition (congruent or incongruent) using subject as a categorical predictor and the three autonomic measures and four acoustic measures as continuous predictors. It revealed that skin conductance response amplitude, cepstral peak prominence, and low-to-high spectral energy ratio were significantly associated with cognitive load condition.

CONCLUSIONS

During speech produced under increased cognitive load, healthy young adults show changes in physiologic markers of heightened autonomic arousal and acoustic measures of voice quality. Future work is necessary to examine these measures in older adults and individuals with voice disorders.

Effect of concurrent walking and interlocutor distance on conversational speech intensity and rate in Parkinson's disease

Previous studies have demonstrated a negative effect of concurrent walking and talking on gait in Parkinson's disease (PD) but there is limited information about the effect of concurrent walking on speech production. The present study examined the effect of sitting, standing, and three concurrent walking tasks (slow, normal, fast) on conversational speech intensity and speech rate in fifteen individuals with hypophonia related to idiopathic Parkinson's disease (PD) and fourteen age-equivalent controls. Interlocuter (talker-to-talker) distance effects and walking speed were also examined. Concurrent walking was found to produce a significant increase in speech intensity, relative to standing and sitting, in both the control and PD groups. Faster walking produced significantly greater speech intensity than slower walking. Concurrent walking had no effect on speech rate. Concurrent walking and talking produced significant reductions in walking speed in both the control and PD groups. In general, the results of the present study indicate that concurrent walking tasks and the speed of concurrent walking can have a significant positive effect on conversational speech intensity. These positive, "energizing" effects need to be given consideration in future attempts to develop a comprehensive model of speech intensity regulation and they may have important implications for the development of new evaluation and treatment procedures for individuals with hypophonia related to PD.

Bidirectional Interference Between Speech and Nonspeech Tasks in Younger, Middle-Aged, and Older Adults

PURPOSE

The purpose of this study was to examine divided attention over a large age range by looking at the effects of 3 nonspeech tasks on concurrent speech motor performance. The nonspeech tasks were designed to facilitate measurement of bidirectional interference, allowing examination of their sensitivity to speech activity. A cross-sectional design was selected to explore possible changes in divided-attention effects associated with age.

METHOD

Sixty healthy participants were separated into 3 groups of 20: younger (20s), middle-aged (40s), and older (60s) adults. Each participant completed a speech task (sentence repetitions) once in isolation and once concurrently with each of 3 nonspeech tasks: a semantic-decision linguistic task, a quantitative-comparison cognitive task, and a manual motor task. The nonspeech tasks were also performed in isolation.

RESULTS

Data from speech kinematics and nonspeech task performance indicated significant task-specific divided attention interference, with divided attention affecting speech and nonspeech measures in the linguistic and cognitive conditions and affecting speech measures in the manual motor condition. There was also a significant age effect for utterance duration.

CONCLUSIONS

The results increase what is known about bidirectional interference between speech and other concurrent tasks as well as age effects on speech motor control.

Attentional demands influence vocal compensations to pitch errors heard in auditory feedback

Auditory feedback is required to maintain fluent speech. At present, it is unclear how attention modulates auditory feedback processing during ongoing speech. In this event-related potential (ERP) study, participants vocalized/a/, while they heard their vocal pitch suddenly shifted downward a ½ semitone in both single and dual-task conditions. During the single-task condition participants passively viewed a visual stream for cues to start and stop vocalizing. In the dual-task condition, participants vocalized while they identified target stimuli in a visual stream of letters. The presentation rate of the visual stimuli was manipulated in the dual-task condition in order to produce a low, intermediate, and high attentional load. Visual target identification accuracy was lowest in the high attentional load condition, indicating that attentional load was successfully manipulated. Results further showed that participants who were exposed to the single-task condition, prior to the dual-task condition, produced larger vocal compensations during the single-task condition. Thus, when participants' attention was divided, less attention was available for the monitoring of their auditory feedback, resulting in smaller compensatory vocal responses. However, P1-N1-P2 ERP responses were not affected by divided attention, suggesting that the effect of attentional load was not on the auditory processing of pitch altered feedback, but instead it interfered with the integration of auditory and motor information, or motor control itself.

Quantitative assessment of interutterance stability: application to dysarthria

PURPOSE

Following recent attempts to quantify articulatory impairment in speech, the present study evaluates the usefulness of a novel measure of motor stability to characterize dysarthria.

METHOD

The study included 8 speakers with ataxic dysarthria (AD), 16 speakers with hypokinetic dysarthria (HD) as a result of Parkinson's disease, and 24 unimpaired control participants. Each participant performed a series of sentence repetitions under habitual, fast, and slow speaking rate conditions. An algorithm to measure utterance-to-utterance spectro-temporal variation (UUV; Cummins, 2009) was used. Speech rate and intelligibility were also measured.

RESULTS

UUV scores were significantly correlated with perceptually based intelligibility scores. There were significant differences in UUV between control speakers and the AD but not the HD groups, presumably because of differences in intelligibility in the samples used and not because of differences in pathology. Habitual speaking rate did not correlate with UUV scores. All speaker groups had greater UUV levels in the slow conditions compared with habitual and fast speaking rates.

CONCLUSIONS

UUV results were consistent with those of other variability indices and thus appear to capture motor control issues in a similar way. The results suggest that the UUV could be developed into an easy-to-use clinical tool that could function as a valid and reliable assessment and outcome measure.

Bidirectional interference between speech and postural stability in individuals with Parkinson's disease

Because people frequently talk while engaged in other activities, and because Parkinson's disease (PD) is known to diminish multi-tasking performance, this study examined dual task interference between speaking and postural stability in nine individuals with PD, seven age-matched, and 10 healthy young controls. Participants repeated a target utterance and performed a rise to toes task in both single and dual task conditions. Diphthong transitions were measured from audio recordings and postural variables reflecting planning, coordination, and stability were derived from a multi-camera motion capture system and force plate recordings. Thus, sensitive measures of both speech and postural control were obtained. The group with PD performed more poorly than both control groups for the isolated postural task, but their single task speech measures did not differ from the controls, in spite of listener ratings which indicated mild-to-moderate dysarthria severity. The group with PD showed evidence of bidirectional dual task interference in that there were reduced diphthong extents and slopes along with smaller, slower, and less stable postural movements. These results indicate that concurrent performance of speech and a challenging postural control task impairs speech and postural stability in persons with PD and may result in greater risk during daily activities.

Patient perceptions of voice therapy adherence

Patient perspectives of behavioral voice therapy, including perspectives of treatment adherence, have not been formally documented. Because treatment adherence is, to a large extent, determined by patient beliefs, assessment of patient perspectives is integral to the study of adherence. Fifteen patients who had undergone at least two sessions of direct voice therapy for a variety of voice disorders/complaints were interviewed about their perspectives on voice therapy, with a particular focus on adherence. Interviews were transcribed and analyzed for content according to qualitative methods. Three common content themes emerged from the transcripts: Voice Therapy is Hard, Make it Happen, and The Match Matters. Findings were compared with reports of patient experiences in other behavioral interventions, such as diet and exercise, and related to existing theoretical models of behavior change and therapeutic process. This study yields information toward the development of scales to measure adherence-related constructs and strategies to improve treatment adherence in voice therapy.