Prolonged Processing Time for Manual and Vocal Responses in Parkinson Disease: A Psychological Refractory Period Paradigm Study.

PURPOSE: The purpose of this study was to examine a potential increased cognitive processing bottleneck within Parkinson disease (PD) by extending a previous overlapping task methodology. Additionally, this study extends previous overlapping task methodology in PD to examine the influence of modality (vocal vs. manual) on response delays in overlapping tasks in PD. METHOD: This study used the psychological refractory period (PRP) paradigm (overlapping-task paradigm) to study processing limitations as participants complete two tasks that increasingly overlap in time. Three levels of temporal overlap of tasks were utilized to vary cognitive demands on manual and vocal response time tasks. Ten participants with PD (PwPD) and 12 participants without PD were included in this study. RESULTS: Participants with PD demonstrated response time delays across temporal overlap conditions (likely indicating motor deficits) along with a larger increase in response delays in the most overlapped, cognitively taxing condition (likely indicating longer central processing bottleneck). Additionally, modality did not influence response times differently in overlapping task conditions or within participant groups. CONCLUSION: An extension of previous overlapping task methodologies within a complex task was successful in demonstrating an increased central processing deficit across manual and vocal response delays in PD, regardless of modality of response.

Linguistic features of dysfluencies in Parkinson Disease.

PURPOSE: The purpose of this study was to examine dysfluency characteristics of individuals with Parkinson Disease (PD) relative to linguistic features of grammatical class and position within word. Few studies have reported dysfluency characteristics of PD relative to these characteristics. Those that do report on these characteristics include one case study and a study of six individuals with PD. No previous research is known to have examined dysfluency related to grammatical class and position within words for a large sample of individuals with PD. METHOD: Dysfluencies from 32 individuals with PD were analyzed according to position within a word and grammatical class. RESULTS: Participants produced significantly more dysfluencies in the initial position of words compared to medial or final positions, and a significantly higher percent dysfluency for content words versus function words. CONCLUSION: Effects of linguistic features of grammatical class and position within a word on dysfluencies are present within a population with PD and are similar to the linguistic features associated with developmental stuttering. Clinical implications of the effect of linguistic features on speech dysfluencies in PD are discussed.

Voicing contrast of stop consonant production in the speech of individuals with Parkinson disease ON and OFF dopaminergic medication.

The aims of this study were to: 1) compare voicing contrast in speakers with Parkinson disease (PD) and healthy controls by comparing the separation of voice onset time (VOT) distributions of voiced and voiceless stop consonants and 2) to determine whether the administration of dopaminergic medication affected VOT separation in speakers with PD. Data from a previous study by Fisher and Goberman (2010) were used to compare the VOT measures obtained from a group of speakers with PD with both ON and OFF medication, and a group of healthy controls. Supplementing the previous findings, the current analysis revealed that individuals with PD exhibited significantly less contrast between voiced and voiceless VOT than that observed in healthy speakers. Medication administration did not affect VOT contrast as no differences in VOT separation were observed between the ON and OFF medication states.

Fluency adaptation in speakers with Parkinson disease: a motor learning perspective.

PURPOSE: Fluency adaptation is characterised by a reduction in stuttering-like behaviours over successive readings of the same speech material and is an effect that is typically observed in developmental stuttering. Prominent theories suggest that short-term motor learning associated with practice explain, in part, fluency adaptation. The current investigation examined the fluency adaptation effect in a group of speakers with Parkinson disease (PD) who exhibited stuttering-like disfluencies. METHOD: Individuals with PD (n = 21) and neurologically healthy controls (n = 19) read a passage five times. Per cent syllables stuttered was measured and calculated for each reading passage. RESULT: Participants in the PD group exhibited significantly more stuttering-like disfluencies than control speakers. Twelve individuals in the PD group exhibited at least three per cent syllable stuttered on at least one reading. Statistical trends revealed that the subgroup of individuals with PD who stuttered exhibited a significant reduction in stuttering moments over the five successive readings. CONCLUSION: A significant fluency adaptation effect was observed for the group of speakers with PD who exhibited stuttering-like disfluencies. Results of the current study are discussed within the framework of the motor learning hypothesis of fluency adaptation.

Speech Motor Sequence Learning: Acquisition and Retention in Parkinson Disease and Normal Aging.

Purpose: The aim of the current investigation was to examine speech motor sequence learning in neurologically healthy younger adults, neurologically healthy older adults, and individuals with Parkinson disease (PD) over a 2-day period. Method: A sequential nonword repetition task was used to examine learning over 2 days. Participants practiced a sequence of 6 monosyllabic nonwords that was retested following nighttime sleep. The speed and accuracy of the nonword sequence were measured, and learning was inferred by examining performance within and between sessions. Results: Though all groups exhibited comparable improvements of the nonword sequence performance during the initial session, between-session retention of the nonword sequence differed between groups. Younger adult controls exhibited offline gains, characterized by an increase in the speed and accuracy of nonword sequence performance across sessions, whereas older adults exhibited stable between-session performance. Individuals with PD exhibited offline losses, marked by an increase in sequence duration between sessions. Conclusions: The current results demonstrate that both PD and normal aging affect retention of speech motor learning. Furthermore, these data suggest that basal ganglia dysfunction associated with PD may affect the later stages of speech motor learning. Findings from the current investigation are discussed in relation to studies examining consolidation of nonspeech motor learning.

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.

Articulatory-acoustic vowel space: Associations between acoustic and perceptual measures of clear speech.

PURPOSE: The current investigation examined the relationship between perceptual ratings of speech clarity and acoustic measures of speech production. Included among the acoustic measures was the Articulatory-Acoustic Vowel Space (AAVS), which provides a measure of working formant space derived from continuously sampled formant trajectories in connected speech. METHOD: Acoustic measures of articulation and listener ratings of speech clarity were obtained from habitual and clear speech samples produced by 10 neurologically healthy adults. Perceptual ratings of speech clarity were obtained from visual-analogue scale ratings and acoustic measures included the AAVS measure, articulation rate and percentage pause. RESULT: Clear speech was characterised by a higher perceptual clarity rating, slower articulation rate, greater percentage pause and larger AAVS compared to habitual speech. Additionally, correlation analysis revealed a significant relationship between the perceptual clear speech effect and the relative clarity-related change in the AAVS and articulation rate measures. CONCLUSION: The current findings suggest that, along with speech rate measures, the recently introduced AAVS is sensitive to changes in speech clarity.

Comparison of self and proxy ratings for voice handicap index and motor-related quality-of-life of individuals with Parkinson's disease.

PURPOSE: Quality-of-life (QoL) consists of health, psychological well-being and communication-related domains. Due to the heterogeneous nature of Parkinson disease (PD), it is important to examine effects of different domains including motor and cognitive performance or motor and speech performance among the same set of individuals. Existing studies indicate mixed findings due to use of different QoL measures and lack of general consensus regarding QoL components. METHOD: The present study examined self and proxy ratings for 20 individuals with PD on Voice Handicap Index (VHI) and PDQ-39 mobility to determine effects on speech and motor-related QoL, respectively. RESULT: There was good level of agreement between self and proxy ratings for PDQ-39 mobility ratings alone. In addition, no overall group differences were found for self and proxy ratings of VHI and PDQ-39 mobility ratings, thus indicating similar perceptions by individuals with PD and their communication partners for speech and motor-related changes associated with PD. Further, no significant correlations between speech and motor-related QoL were found, thereby suggesting these domains to be independent of each other. CONCLUSION: The present study indicates the need to consider both self and proxy reports to understand the impact of PD on a person's overall functioning.

Articulatory-acoustic vowel space: application to clear speech in individuals with Parkinson's disease.

BACKGROUND/PURPOSE: Individuals with Parkinson disease (PD) often exhibit decreased range of movement secondary to the disease process, which has been shown to affect articulatory movements. A number of investigations have failed to find statistically significant differences between control and disordered groups, and between speaking conditions, using traditional vowel space area measures. The purpose of the current investigation was to evaluate both between-group (PD versus control) and within-group (habitual versus clear) differences in articulatory function using a novel vowel space measure, the articulatory-acoustic vowel space (AAVS). METHODS: The novel AAVS is calculated from continuously sampled formant trajectories of connected speech. In the current study, habitual and clear speech samples from twelve individuals with PD along with habitual control speech samples from ten neurologically healthy adults were collected and acoustically analyzed. In addition, a group of listeners completed perceptual rating of speech clarity for all samples. RESULTS: Individuals with PD were perceived to exhibit decreased speech clarity compared to controls. Similarly, the novel AAVS measure was significantly lower in individuals with PD. In addition, the AAVS measure significantly tracked changes between the habitual and clear conditions that were confirmed by perceptual ratings. CONCLUSIONS: In the current study, the novel AAVS measure is shown to be sensitive to disease-related group differences and within-person changes in articulatory function of individuals with PD. Additionally, these data confirm that individuals with PD can modulate the speech motor system to increase articulatory range of motion and speech clarity when given a simple prompt. LEARNING OUTCOMES: The reader will be able to (i) describe articulatory behavior observed in the speech of individuals with Parkinson disease; (ii) describe traditional measures of vowel space area and how they relate to articulation; (iii) describe a novel measure of vowel space, the articulatory-acoustic vowel space and its relationship to articulation and the perception of speech clarity.

Long-time average spectrum in individuals with Parkinson disease.

BACKGROUND: Various methods of acoustic analysis have been used to describe phonatory deficits in Parkinson disease (PD), including long-time average spectrum (LTAS) analysis. OBJECTIVE: The aim of this study was to utilize the LTAS to investigate laryngeal deficits in individuals with PD. METHODS: Twenty-eight individuals with idiopathic PD and 10 controls were participants for this study. An LTAS was generated from a standard reading sample and analyzed using the following measurements: Mean spectral energy (MSE), first spectral peak, spectral tilt (ST), three spectral slope (SS) measures (i.e., SSF0-1kHz, SS1-5kHz, and SS ratio) and four spectral moments (mean, standard deviation, skewness, and kurtosis). RESULTS: Individuals with PD were found to demonstrate significantly lower MSE, spectral mean and spectral SD, along with higher spectral skewness compared to control speakers. Furthermore, ST was positively correlated with self-rated symptom severity and self-rated medication effectiveness for individuals with PD. CONCLUSIONS: The LTAS findings were consistent with either reduced vocal fold adduction or vocal fold bowing in individuals with PD compared to control speakers. Additionally, vocal fold adductory changes were one possible explanation for correlations between LTAS and self-ratings of medication effectiveness and disease severity.

Presence of stop bursts and multiple bursts in individuals with Parkinson disease.

Studies have reported that individuals with Parkinson Disease (PD) have imprecise articulation of stop consonants due to either slowness of articulators or decreased closure strength. The moment of release for stop consonants, called the burst, has been previously studied in individuals with PD and in other disorders. Multiple bursts (MBs) on the same stop consonant have been reported previously in some motor speech disorders, but no studies are known to have examined MBs in individuals with PD. The current study looked at the occurrences of bursts and MBs in initial stop consonants produced by nine individuals with PD (ON and OFF medication) and nine control speakers. Individuals with PD produced fewer overall bursts compared to control participants. In terms of place of articulation, individuals with PD primarily had loss of bursts in bilabial stops. In addition, individuals with PD had more MBs than control speakers, primarily in alveolars. Finally, no dopamine-related medication effects were found for occurrences of bursts or MBs in individuals with PD. Overall, the study provided evidence for loss of bursts and presence of MBs for stop consonants produced by individuals with PD.

Voice onset time in Parkinson disease.

UNLABELLED: Research has found that speaking rate has an effect on voice onset time (VOT). Given that Parkinson disease (PD) affects speaking rate, the purpose of this study was to examine VOT with the effect of rate removed (VOT ratio), along with the traditional VOT measure, in individuals with PD. VOT and VOT ratio were examined in 9 individuals with PD (before and after taking medication), along with 9 matched controls. Place of articulation and vowel height had significant effects on VOT and VOT ratio for all groups, and there were no PD versus control differences. PD medication had a greater effect on VOT than VOT ratio, reflecting a rate-related VOT change rather than a pure VOT change. These data support the usefulness of examining both VOT and VOT ratio with individuals with PD, as this allows for dissociation between rate-related VOT changes and true VOT changes. LEARNING OUTCOMES: The reader will be able to understand and describe: (1) voice onset time (VOT) and VOT ratio; (2) how VOT and VOT ratio are affected in individuals with Parkinson disease; and (3) the effect of medication on VOT and VOT ratio.

The effect of positioning on infant cries: implications for sudden infant death syndrome.

OBJECTIVE: A definitive cause for sudden infant death syndrome (SIDS) has not yet been identified, but some theories point to laryngeal or respiratory causes, in addition to theories of reduced arousal or reduced autonomic response. The occurrence of SIDS has dropped since the movement to place newborns to sleep in the supine position; however, some research has found a respiratory disadvantage for infants in this position. The current paper studied acoustic characteristics of infant pain cries to determine the potential differences related to prone versus supine positioning. METHODS: Fifty-one newborn infant cries were recorded during and following a blood draw screening procedure, with infants placed either in the supine or prone position. All infants were healthy, full-term infants. Complete crying episodes were audio-recorded, and results were based on compositional analysis and long-time average spectrum analysis across each crying episode. RESULTS: Spectral analysis revealed acoustic differences related to infant positioning, and acoustic analysis also revealed that there were no respiratory differences between supine-positioned and prone-positioned infants. Overall, the acoustic differences suggest decreased arousal and/or a decreased response to pain for healthy infants recorded in the prone position. CONCLUSIONS: As decreased arousal and prone positioning have been seen as possible causative factors for SIDS, the current results are seen as a successful step in evaluating the possibility of using acoustic analysis of infant cries as a means of evaluating SIDS risk for healthy infants.

Revisiting speech rate and utterance length manipulations in stuttering speakers.

UNLABELLED: The goal of this study was to evaluate stuttering frequency across a multidimensional (2x2) hierarchy of speech performance tasks. Specifically, this study examined the interaction between changes in length of utterance and levels of speech rate stability. Forty-four adult male speakers participated in the study (22 stuttering speakers and 22 non-stuttering speakers). Participants were audio and video recorded while producing a spontaneous speech task and four different experimental speaking tasks. The four experimental speaking tasks involved reading a list of 45 words and a list 45 phrases two times each. One reading of each list involved speaking at a steady habitual rate (habitual rate tasks) and another reading involved producing each list at a variable speaking rate (variable rate tasks). For the variable rate tasks, participants were directed to produce words or phrases at randomly ordered slow, habitual, and fast rates. The stuttering speakers exhibited significantly more stuttering on the variable rate tasks than on the habitual rate tasks. In addition, the stuttering speakers exhibited significantly more stuttering on the first word of the phrase length tasks compared to the single word tasks. Overall, the results indicated that varying levels of both utterance length and temporal complexity function to modulate stuttering frequency in adult stuttering speakers. Discussion focuses on issues of speech performance according to stuttering severity and possible clinical implications. LEARNING OUTCOMES: The reader will learn about and be able to: (1) describe the mediating effects of length of utterance and speech rate on the frequency of stuttering in stuttering speakers; (2) understand the rationale behind multidimensional skill performance matrices; and (3) describe possible applications of motor skill performance matrices to stuttering therapy.

Fundamental frequency change during offset and onset of voicing in individuals with Parkinson disease.

SUMMARY: After years of treatment with the medication levodopa, most individuals with Parkinson disease (PD) experience fluctuations in response to their medications. Although relatively consistent perceptual voice improvements have been documented to correspond with these fluctuations, consistent quantitative data to support this finding are lacking. This mismatch may have occurred because most of this phonation research has centered on long-term phonatory measures (ie, across speaking samples and prolonged vowel tasks). The current study examined short-term phonatory behavior in individuals with PD, specifically examining fundamental frequency (F0) at the offset and onset of phonation, before and after a voiceless consonant. The F0 analysis at phonatory offset supported the conclusion that individuals with PD have difficulty with the rapid offset of voicing, and that they are stopping vocal fold vibration primarily through vocal fold abduction (without adding tension). The F0 analysis at phonatory onset revealed that all groups use some laryngeal tension at the initiation of voicing. The tension was lowest for the PD participants who were in their OFF medication state, and it was highest for the age-matched control participants and the PD participants in their ON medication states.

Acoustic characteristics of crying in infantile laryngomalacia.

The purpose of this study was to add to the extant data base of acoustic cry studies by profiling the condition of laryngomalacia. We hypothesized that the acoustic characteristics of crying produced by an infant with laryngomalacia would differ compared to previously reported cry data for normal infants. An entire episode of crying was audio recorded and acoustically analyzed for the occurrence of expiratory and inspiratory cry segments, as well as the long-time average spectral (LTAS) characteristics. Results obtained for the infant were found to be considerably different from what has been previously reported for normal infants. The overall duration of the infant's crying episode was longer, with proportionately fewer expiratory phonations and more inspiratory phonations compared to normal infants. The LTAS results were reflective of aperiodic components in the glottal source spectrum. Collectively, the infant's unusual crying aspects were not limited solely to those acoustic features resulting from a prolapse of supraglottic soft tissue, and therefore provide new insight into the vocal fold vibratory behavior characterizing infantile laryngomalacia.

Acoustic analysis of clear versus conversational speech in individuals with Parkinson disease.

UNLABELLED: A number of studies have been devoted to the examination of clear versus conversational speech in non-impaired speakers. The purpose of these previous studies has been primarily to help increase speech intelligibility for the benefit of hearing-impaired listeners. The goal of the present study was to examine differences between conversational and clear speech in individuals with Parkinson disease (PD). Twelve individuals were recorded producing conversational and clear speech. Acoustic analysis revealed that individuals with PD used some of the same clear speech strategies used by non-impaired speakers. Specifically, clear speech in PD was characterized by decreased articulation rate, increased mean fundamental frequency (F(o)), and increased speaking F(o)S.D. compared to conversational speech. The discussion examines the possibility that individuals with PD may have been independently applying a clear speech strategy based on their habitually increased percent pause values. Discussion also focuses on implications of the present findings to management of individuals with PD, and research implications. LEARNING OUTCOMES: As a result of this activity, the participant will be able to (1) describe the characteristics of clear speech produced by non-disordered individuals, (2) describe the acoustic characteristics of clear and conversational speech produced by individuals with Parkinson disease; and (3) describe the strategies individuals with Parkinson disease use when asked to produce clear speech.

Correlation between acoustic speech characteristics and non-speech motor performance in Parkinson Disease.

BACKGROUND: Research has found that non-speech motor deficits in Parkinson Disease (PD) can be consistently improved by levodopa medications and surgical treatment, but that speech and voice are only partially responsive to treatment. This has led to the assertion that speech is an axial (non-peripheral) feature of PD, along with other features that are only partially responsive to treatment (e.g., postural stability and gait). The current study tested this assertion via examination of the relationship between multiple measures of speech production and multiple measures of non-speech movement in individuals with PD. MATERIAL/METHODS: Nine individuals with idiopathic PD were studied, and all participants were taking levodopa-carbidopa medication. Motor performance was examined using the motor portion of the Unified Parkinson's Disease Rating Scale, and speech was examined via acoustic analysis of phonation, articulation, and prosody. RESULTS: Seven of sixteen speech acoustic measures (FoSD in vowels, F2 slope for /u/ and /ae/, FoSD in reading, articulation rate in monologue, and percent pause in reading and monologue) were significantly correlated with non-speech movements. Results suggested that speech measures are correlated with both axial motor symptoms (e.g., gait, facial expression, posture, postural stability) and non-axial motor symptoms (e.g., rest tremor, left and right bradykinesia, postural tremor). CONCLUSIONS: It has been hypothesized that axial symptoms of PD are more purely dopaminergic, and non-axial symptoms are related to non-dopaminergic lesions. Therefore, the current results indicate that certain speech deficits in PD may result from dopaminergic lesions, while others appear to result from non-dopaminergic lesions.

Parkinsonian speech disfluencies: effects of L-dopa-related fluctuations.

UNLABELLED: The excess dopamine theory of stuttering (Wu et al., 1997) contends that stuttering may be related to excess levels of the neurotransmitter dopamine in the brain. As Parkinson's disease (PD) patients commonly exhibit changes in dopamine levels accompanied by changes in motor performance, the present study examined disfluency in PD patients to gain information on the role of dopamine in speech disfluencies. Nine PD patients with no history of developmental stuttering were recorded once before and twice after taking their morning medication (on separate days). They read a passage and produced a monologue. Within-word and overall speech disfluencies were calculated at each recording. Through motor testing, it was inferred that participants had relatively low dopamine levels before taking medication, and relatively high dopamine levels after taking medication. There were no group changes in disfluency levels when the low-dopamine and high-dopamine states were compared. There were, however, significant differences in percent disfluencies between the PD participants and age-matched controls. The results of this study do not strongly support the excess dopamine theory of stuttering. Rather, the disfluency changes exhibited by individual participants support a hypothesis that speech disfluencies may be related to increases or decreases in dopamine levels in the brain. EDUCATIONAL OBJECTIVES: The reader will learn about: (1). the characteristics of disfluent speech exhibited by speakers with Parkinson's disease. (2). The effect of L-dopa based medications on disfluencies of Parkinsonian speakers. (3). The complex role brain dopamine levels may play in disfluent speaking behavior.

Acoustic analysis of parkinsonian speech I: speech characteristics and L-Dopa therapy.

This paper reviews the literature pertaining to Parkinson's disease (PD) and the speech dysfunction typically associated with PD, including the effects on respiration, phonation, articulation, resonance, and prosody. The effect of treatment with the drug L-Dopa is also examined, along with the effect of L-Dopa treatment on Parkinsonian speech. This paper is the first of a two-part series. Part two examines the literature pertaining to the fluctuations that can occur during treatment with L-Dopa, the speech changes associated with these fluctuations, and methodological issues affecting the examination of fluctuations and PD speech.