Effects of Speech Cues on Acoustics and Intelligibility of Korean-Speaking Children With Cerebral Palsy

PURPOSE

Reduced speech intelligibility is often a hallmark of children with dysarthria secondary to cerebral palsy (CP), but effects of speech strategies for increasing intelligibility are understudied, especially in children who speak languages other than English. This study examined the effects of (the Korean translation of) two cues, "speak with your big mouth" and "speak with your strong voice," on speech acoustics and intelligibility of Korean-speaking children with CP.

METHOD

Fifteen Korean-speaking children with CP repeated words and sentences in habitual, big mouth, and strong voice conditions. Acoustic analyses were performed and intelligibility was assessed by means of 90 blinded listeners' ease-of-understanding (EoU) ratings and percentage of words correctly transcribed (PWC).

RESULTS

In response to both cues, children's vocal intensity and utterance duration increased significantly and differentially, whereas their vowel space area gains did not reach statistical significance. EoU increased significantly in the big mouth condition at word, but not sentence, level, whereas in the strong voice condition, EoU increased significantly at both levels. PWC increases were not statistically significant. Considerable variability in children's responses to cues was noted overall.

CONCLUSIONS

Korean-speaking children with CP modify their speech styles differentially when provided with cues aimed to increase their articulatory working space and vocal intensity. The results provide preliminary support for the use of the strong voice cue, in particular, to increase EoU. While the findings do not offer conclusive evidence of the intelligibility benefits of these cues, investigation with a larger sample size should provide further insight into optimal cueing strategies for increasing intelligibility in this population. Implications for language-specific versus language-independent treatment approaches are discussed.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.25521052.

"Take Us Into Account": Perspectives of Family Members of People With Parkinson's Disease Regarding Speech-Language Pathology Intervention

PURPOSE

While communication changes associated with Parkinson's disease (PD) have been documented, research on the impact of these changes on family members is just beginning to emerge. With this new focus on family, questions arise as to how well speech-language pathology services address their needs communicating with their loved one with PD. The purpose of this study was to explore the experiences of family members of people with PD (PwPD) and their recommendations for speech-language pathology services that incorporated their needs.

METHOD

Seventeen spouses/partners of PwPD participated in focus groups that were recorded, transcribed, and analyzed using thematic analyses.

RESULTS

Three themes emerged, all focusing around the central tenet that the experiences of family members, and hence their need for speech-language pathology support, transitioned through the stages of PD progression. Theme 1 summarized increasing burdens on family to manage communication as PD progressed beyond a brief period of independent strategy use by PwPD. Theme 2 highlighted multifactorial contributors to communication burdens on families, with cognitive impairments being the most underrecognized. Theme 3 illustrated how families wanted more intervention options from speech-language pathologists (SLPs) that included them, but with a tailored approach for PD stages and personal preferences.

CONCLUSIONS

When SLPs provide families with either generic communication strategies or strategies that do not fit the individualized needs of PwPD and their families, we may inadvertently be increasing the burden on families. There is a need for systematic, evidence-based, family-centered interventions that include, but go beyond, current speech-focused interventions to meet the shared communication needs of PwPD and their families.

A qualitative study of reflective practice in the workplace. Speech-language pathologists have their say

PURPOSE

Engaging in reflective practice (RP) and demonstrating reflective abilities is an essential graduate skill for speech-language pathologists (SLPs), yet limited studies have examined the perspectives of practicing SLPs and how and why they engage in RP. This qualitative study aimed to examine SLPs' experiences and perspectives of RP in diverse workplaces.

METHOD

Individual semi-structured interviews were conducted with 30 SLPs working in health, education, or private practice sectors. Interviews were analysed using thematic analysis.

RESULT

Three themes were developed from the data, describing what SLPs use RP for, what SLPs perceive as important in order to engage in RP in the workplace, as well as the barriers they have identified, and how SLPs have observed a change in engaging in RP as they have progressed in their careers.

CONCLUSION

SLPs described that RP is valued in the workplace for supporting client focused care, problem-solving, and lifelong learning. SLPs wanted time to be protected for RP at all stages of their career and valued the relationships with others as contributing positively to RP. Perceptions of and engagement in RP changed in relation to SLPs' clinical experience. Implications for clinical practice are discussed.

Acoustic Predictors of Ease of Understanding in Spanish Speakers With Dysarthria Associated With Parkinson's Disease

PURPOSE

The purpose of this study was to examine selected baseline acoustic features of hypokinetic dysarthria in Spanish speakers with Parkinson's disease (PD) and identify potential acoustic predictors of ease of understanding in Spanish.

METHOD

Seventeen Spanish-speaking individuals with mild-to-moderate hypokinetic dysarthria secondary to PD and eight healthy controls were recorded reading a translation of the Rainbow Passage. Acoustic measures of vowel space area, as indicated by the formant centralization ratio (FCR), envelope modulation spectra (EMS), and articulation rate were derived from the speech samples. Additionally, 15 healthy adults rated ease of understanding of the recordings on a visual analogue scale. A multiple linear regression model was implemented to investigate the predictive value of the selected acoustic parameters on ease of understanding.

RESULTS

Listeners' ease of understanding was significantly lower for speakers with dysarthria than for healthy controls. The FCR, EMS from the first 10 s of the reading passage, and the difference in EMS between the end and the beginning sections of the passage differed significantly between the two groups of speakers. Findings indicated that 67.7% of the variability in ease of understanding was explained by the predictive model, suggesting a moderately strong relationship between the acoustic and perceptual domains.

CONCLUSIONS

Measures of envelope modulation spectra were found to be highly significant model predictors of ease of understanding of Spanish-speaking individuals with hypokinetic dysarthria associated with PD. Articulation rate was also found to be important (albeit to a lesser degree) in the predictive model. The formant centralization ratio should be further examined with a larger sample size and more severe dysarthria to determine its efficacy in predicting ease of understanding.

Acquired Stuttering in Parkinson's Disease

Background

Parkinson's disease frequently causes communication impairments, but knowledge about the occurrence of new-onset stuttering is limited.

Objectives

To determine the presence of acquired neurogenic stuttering and its relationship with cognitive and motor functioning in individuals with Parkinson's disease.

Method

Conversation, picture description, and reading samples were collected from 100 people with Parkinson's disease and 25 controls to identify the presence of stuttered disfluencies (SD) and their association with neuropsychological test performance and motor function.

Results

Participants with Parkinson's disease presented with twice as many stuttered disfluencies during conversation (2.2% ± 1.8%SD) compared to control participants (1.2% ± 1.2%SD; P < 0.01). 21% of people with Parkinson's disease (n = 20/94) met the diagnostic criterion for stuttering, compared with 1/25 controls. Stuttered disfluencies also differed significantly across speech tasks, with more disfluencies during conversation compared to reading (P < 0.01). Stuttered disfluencies in those with Parkinson's disease were associated with longer time since disease onset (P < 0.01), higher levodopa equivalent dosage (P < 0.01), and lower cognitive (P < 0.01) and motor scores (P < 0.01).

Conclusion

One in five participants with Parkinson's disease presented with acquired neurogenic stuttering, suggesting that speech disfluency assessment, monitoring and intervention should be part of standard care. Conversation was the most informative task for identifying stuttered disfluencies. The frequency of stuttered disfluencies was higher in participants with worse motor functioning, and lower cognitive functioning. This challenges previous suggestions that the development of stuttered disfluencies in Parkinson's disease has purely a motoric basis.

Written reflective practice abilities of SLT students across the degree programme

BACKGROUND

Written reflective practice (WRP) is a teaching tool used across speech-language therapy (SLT) clinical education programmes. The process aims to support the development of reflective skills required for the workplace (e.g., problem-solving and self-evaluation).

AIMS

This cross-sectional and repeated-measures study design investigated students' demonstration of breadth of WRP across the clinical education programme.

METHODS & PROCEDURES

The participants were 77 undergraduate SLT students in their first, second or final professional year of the clinical programme. Participants wrote critical reflections following an interaction with a client/s as part of their clinical education experiences. Formative feedback was provided after each written reflection (WR). In total four WRs per participant were coded for breadth of WRP using a modification of Plack et al.'s coding schema from 2005. This was completed for each of the four time points across the academic year for each professional year.

OUTCOMES & RESULTS

There was a statistically significant association between time (i.e., professional year of the programme) and likelihood of demonstration of breadth of reflection for the lower level reflective element of 'attend' and higher level reflective element of 're-evaluate'. A positive trend between time and likelihood of demonstration of breadth of reflection was seen for the lower level element of 'reflection-for-action'. Final-professional-year students exhibited significant enhancements in the higher level elements (e.g., 'premise') compared with first- and second-professional-year students.

CONCLUSIONS & IMPLICATIONS

This group of SLT students exhibited significant change in breadth of WRP across the degree programme. This finding has positive implications for facilitating WRP with students and using the current coding framework in clinical programmes.

WHAT THIS PAPER ADDS

What is already known on this subject WRP is one form of reflective practice (RP) used in SLT, allied health, medical and nursing clinical education programmes. Researchers have suggested that RP skills develop over time for students. Previously, studies examining WRP have focused on one off assessment of skill or over a timeframe of 6-10 weeks. Here, we examine SLT students' WRP skills across the degree programme. What this paper adds to existing knowledge SLT students exhibited significant positive change in breadth of WRP across the degree programme as their clinical experience increased. Our results provide quantitative information in support of using RP as a learning tool throughout clinical education programmes for SLT. What are the potential or actual clinical implications of this work? This study offers support for educators of SLT students; for example, how educators can assess WRP, and how educators can foster SLT student skill development with formative feedback and reflective questioning. This study also offers support for student SLT, for example, describing how WRP can be part of their individualized learning approach and provide a purposeful examination of self and clinical skill development.

The Effects of Intensive Voice Treatment in Mandarin Speakers With Parkinson's Disease: Acoustic and Perceptual Findings

PURPOSE

This study investigated the effects of intensive voice treatment on subjective and objective measures of speech production in Mandarin speakers with hypokinetic dysarthria.

METHOD

Nine Mandarin speakers with hypokinetic dysarthria due to Parkinson's disease received 4 weeks of intensive voice treatment (4 × 60 min per week). The speakers were recorded reading a passage before treatment (PRE), immediately after treatment (POST), and at 6-month follow-up (FU). Listeners (n = 15) rated relative ease of understanding (EOU) of paired speech samples on a visual analogue scale. Acoustic analyses were performed. Changes in EOU, vocal intensity, global and local fundamental frequency (f _o) variation, speech rate, and acoustic vowel space area (VSA) were examined.

RESULTS

Increases were found in EOU and vocal intensity from PRE to POST and from PRE to FU, with no change found from POST to FU. Speech rate increased from PRE to POST, with limited evidence of an increase from PRE to FU and no change from POST to FU. No changes in global or local f _o variation or in VSA were found.

CONCLUSIONS

Intensive voice treatment shows promise for improving speech production in Mandarin speakers with hypokinetic dysarthria. Vocal intensity, speech rate, and, crucially, intelligibility, may improve for up to 6 months posttreatment. In contrast, f _o variation and VSA may not increase following the treatment.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.19529017.

Perceptual and Acoustic Effects of Dual-Focus Speech Treatment in Children With Dysarthria

Purpose Children with dysarthria secondary to cerebral palsy may experience reduced speech intelligibility and diminished communicative participation. However, minimal research has been conducted examining the outcomes of behavioral speech treatments in this population. This study examined the effect of Speech Intelligibility Treatment (SIT), a dual-focus speech treatment targeting increased articulatory excursion and vocal intensity, on intelligibility of narrative speech, speech acoustics, and communicative participation in children with dysarthria. Method American English-speaking children with dysarthria (n = 17) received SIT in a 3-week summer camplike setting at Columbia University. SIT follows motor-learning principles to train the child-friendly, dual-focus strategy, "Speak with your big mouth and strong voice." Children produced a story narrative at baseline, immediate posttreatment (POST), and at 6-week follow-up (FUP). Outcomes were examined via blinded listener ratings of ease of understanding (n = 108 adult listeners), acoustic analyses, and questionnaires focused on communicative participation. Results SIT resulted in significant increases in ease of understanding at POST, that were maintained at FUP. There were no significant changes to vocal intensity, speech rate, or vowel spectral characteristics, with the exception of an increase in second formant difference between vowels following SIT. Significantly enhanced communicative participation was evident at POST and FUP. Considerable variability in response to SIT was observed between children. Conclusions Dual-focus treatment shows promise for improving intelligibility and communicative participation in children with dysarthria, although responses to treatment vary considerably across children. Possible mechanisms underlying the intelligibility gains, enhanced communicative participation, and variability in treatment effects are discussed.

Predicting Montreal Cognitive Assessment Scores From Measures of Speech and Language

Purpose This study examined the relationship between measurements derived from spontaneous speech and participants' scores on the Montreal Cognitive Assessment. Method Participants (N = 521) aged between 64 and 97 years completed the cognitive assessment and were prompted to describe an early childhood memory. A range of acoustic and linguistic measures was extracted from the resulting speech sample. A least absolute shrinkage and selection operator approach was used to model the relationship between acoustic, lexical, and demographic information and participants' scores on the cognitive assessment. Results Using the covariance test statistic, four important variables were identified, which, together, explained 16.52% of the variance in participants' cognitive scores. Conclusions The degree to which cognition can be accurately predicted through spontaneously produced speech samples is limited. Statistically significant relationships were found between specific measurements of lexical variation, participants' speaking rate, and their scores on the Montreal Cognitive Assessment.

An epidemiological profile of communication disability among older adults with complex needs: A national cross-sectional study

Purpose: Research on the prevalence of communication disability among community living older adults is scant, and often suffers from limitations. Using a national database, this study presents an epidemiological profile of communication disability in older community residents within New Zealand and examines whether ethnic populations are disproportionately represented.Method: Since 2012, all New Zealand community care recipients have undergone a standardised needs assessment, which includes questions directed at expressive and receptive language abilities. Those assessed between 1 September 2012 and 31 January 2016, aged ≥65 years, and who provided consent were included. Directly standardised prevalence estimates were calculated and logistic regression used to investigate age, sex and ethnic differences.Result: Overall, 71 859 people were eligible (mean age = 82.7 years, 61% female, 89.2% European/other), with 30.6% and 36.2% exhibiting at least some expression and comprehension communication disability, respectively. Māori, Pasifika and Asian people, males and those who were older were more likely to have at least some communication disability compared to their European/other, female and younger counterparts.Conclusion: Communication disability is common among older adults. With the increased provision of home-based integrated models of care, the impact of communication disability on service seeking and delivery must be recognised and accommodated.

Hearing ability is not a risk factor for admission to aged residential care of older persons in New Zealand

Aged residential care (ARC) admission needs are increasing beyond the available capacity in many countries, including New Zealand. Therefore, identifying modifiable factors which may prevent or delay ARC admissions is of international importance. Hearing impairment is common among older adults and thought to be an important predictor, although the current evidence-base is equivocal. Using the largest national database to date, competing-risk regression analysis was undertaken on 34,277 older adults having standardised home care assessments between 1 July 2012 and 31 May 2014, aged ≥65 years, and still living in the community 30 days after that assessment. Minimal hearing difficulty was reported by 10,125 (29.5%) participants, moderate difficulty by 5,046 (14.7%), severe difficulty/no hearing by 1,334 (3.9%), while 17,769 (51.8%) participants reported adequate hearing. By 30 June 2014, the study end-point, 6,389 (18.6%) participants had an ARC admission while 6,082 (17.7%) had died. In unadjusted competing-risk regression analyses, treating death as a competing event, hearing ability was significantly associated with ARC admission (p < 0.001). However, in adjusted analyses, this relationship was completely confounded by other variables (p = 0.67). This finding implies that screening for hearing loss among community-living older adults is unlikely to impact on ARC admission rates.

Acoustic and Perceptual Consequences of Speech Cues for Mandarin Speakers With Parkinson's Disease

Purpose This study investigated the effects of cueing for increased loudness and reduced speech rate on scaled intelligibility and acoustics of speech produced by Mandarin speakers with hypokinetic dysarthria due to Parkinson's disease (PD). Method Eleven speakers with PD read passages in habitual, loud, and slow speaking conditions. Fifteen listeners rated ease of understanding (EOU) of the speech samples on a visual analog scale. Effects of the cues on EOU, vocal loudness, pitch range, pause duration and frequency, articulation rate, and vowel space, as well as relationships between EOU gains and acoustic features, were analyzed. Results EOU increased significantly in the loud condition only. The loud cue resulted in increased intensity, and the slow cue resulted both in reduced articulation rate and increased pause frequency. In the loud condition, EOU increased significantly as intensity increased and vowel centralization decreased. In the slow condition, EOU tended to increase as intensity increased and vowel centralization decreased but did not reach statistical significance. Conclusion Cueing for loud speech may yield greater EOU gains than cueing for slow speech in Mandarin speakers with PD. Theoretical and clinical implications are discussed, although further investigations with more participants and a larger range of dysarthria severity are warranted.

Predicting Intelligibility Gains in Individuals With Dysarthria From Baseline Speech Features

PURPOSE

Across the treatment literature, behavioral speech modifications have produced variable intelligibility changes in speakers with dysarthria. This study is the first of two articles exploring whether measurements of baseline speech features can predict speakers' responses to these modifications.

METHODS

Fifty speakers (7 older individuals and 43 speakers with dysarthria) read a standard passage in habitual, loud, and slow speaking modes. Eighteen listeners rated how easy the speech samples were to understand. Baseline acoustic measurements of articulation, prosody, and voice quality were collected with perceptual measures of severity.

RESULTS

Cues to speak louder and reduce rate did not confer intelligibility benefits to every speaker. The degree to which cues to speak louder improved intelligibility could be predicted by speakers' baseline articulation rates and overall dysarthria severity. Improvements in the slow condition could be predicted by speakers' baseline severity and temporal variability. Speakers with a breathier voice quality tended to perform better in the loud condition than in the slow condition.

CONCLUSIONS

Assessments of baseline speech features can be used to predict appropriate treatment strategies for speakers with dysarthria. Further development of these assessments could provide the basis for more individualized treatment programs.

Predicting Intelligibility Gains in Dysarthria Through Automated Speech Feature Analysis

PURPOSE

Behavioral speech modifications have variable effects on the intelligibility of speakers with dysarthria. In the companion article, a significant relationship was found between measures of speakers' baseline speech and their intelligibility gains following cues to speak louder and reduce rate (Fletcher, McAuliffe, Lansford, Sinex, & Liss, 2017). This study reexamines these features and assesses whether automated acoustic assessments can also be used to predict intelligibility gains.

METHOD

Fifty speakers (7 older individuals and 43 with dysarthria) read a passage in habitual, loud, and slow speaking modes. Automated measurements of long-term average spectra, envelope modulation spectra, and Mel-frequency cepstral coefficients were extracted from short segments of participants' baseline speech. Intelligibility gains were statistically modeled, and the predictive power of the baseline speech measures was assessed using cross-validation.

RESULTS

Statistical models could predict the intelligibility gains of speakers they had not been trained on. The automated acoustic features were better able to predict speakers' improvement in the loud condition than the manual measures reported in the companion article.

CONCLUSIONS

These acoustic analyses present a promising tool for rapidly assessing treatment options. Automated measures of baseline speech patterns may enable more selective inclusion criteria and stronger group outcomes within treatment studies.

Variables associated with communicative participation in Parkinson's disease and its relationship to measures of health-related quality-of-life

PURPOSE

Communication disorders associated with Parkinson's disease (PD) often lead to restricted participation in life roles, yet there is a limited understanding of influencing factors and few quantitative measurement tools available. This study aimed to identify variables associated with communicative participation in PD and to examine the relationship between the Communicative Participation Item Bank (CPIB) and existing health-related quality-of-life (HRQoL) measures.

METHOD

Self-report data from 378 participants with PD from the US and New Zealand were analysed. Data included responses to the CPIB, PD Questionnaire-8, sub-scales of the Global Health instrument from the Patient Reported Outcomes Measurement Information System (PROMIS) and additional self-report instruments.

RESULT

Greater perceived speech disorder, lower levels of speech usage, fatigue, cognitive and emotional problems and swallowing difficulties were associated with lower levels of communicative participation. Participants' age significantly influenced findings, interacting with country of residence, sex and speech usage. Scores on the CPIB were moderately correlated with HRQoL measures.

CONCLUSION

Communicative participation in PD is complex and influenced by both demographic and disease-based variables, necessitating a broader view of the communicative experiences of those with PD. Measurement of communicative participation as a separate construct to existing HRQoL measures is recommended.

Acoustic and Perceptual Consequences of Speech Cues for Children With Dysarthria

PURPOSE

Reductions in articulatory working space and vocal intensity have been linked to intelligibility deficits in children with dysarthria due to cerebral palsy. However, few studies have examined the outcomes of behavioral treatments aimed at these underlying impairments or investigated which treatment cues might best facilitate improved intelligibility. This study assessed the effects of cues targeting clear speech (i.e., "Speak with your big mouth") and greater vocal intensity (i.e., "Speak with your strong voice") on acoustic measures of speech production and intelligibility.

METHOD

Eight children with spastic dysarthria due to cerebral palsy repeated sentence- and word-level stimuli across habitual, big mouth, and strong voice conditions. Acoustic analyses were conducted, and 48 listeners completed orthographic transcription and scaled intelligibility ratings.

RESULTS

Both cues resulted in significant changes to vocal intensity and speech rate although the degree of change varied by condition. In a similar manner, perceptual analysis revealed significant improvements to intelligibility with both cues; however, at the single-word level, big mouth outperformed strong voice.

CONCLUSION

Children with dysarthria are capable of changing their speech styles differentially in response to cueing. Both the big mouth and strong voice cues hold promise as intervention strategies to improve intelligibility in this population.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.5116843.

Acoustic and perceptual speech characteristics of native Mandarin speakers with Parkinson's disease

This study examines acoustic features of speech production in speakers of Mandarin with Parkinson's disease (PD) and relates them to intelligibility outcomes. Data from 11 participants with PD and 7 controls are compared on several acoustic measures. In speakers with PD, the strength of association between these measures and intelligibility is investigated. Speakers with PD exhibited significant differences in fundamental frequency, pitch variation, vowel space, and rate relative to controls. However, in contrast to the English studies, speech rate was consistently slow and most strongly correlated with intelligibility. Thus, acoustic cues that strongly influence intelligibility in PD may vary cross-linguistically.

Effect of Dysarthria Type, Speaking Condition, and Listener Age on Speech Intelligibility

PURPOSE

The aim of this study was to examine the effect of loud and slow speech cues on younger and older listeners' comprehension of dysarthric speech, specifically, (a) whether one strategy, as opposed to the other, promoted greater intelligibility gains for different speaker groups; (b) whether older and younger listeners' understandings were differentially affected by these strategies; and (c) which acoustic changes best predicted intelligibility gain in individual speakers.

METHOD

Twenty younger and 40 older listeners completed a perceptual task. Six individuals with dysarthria produced phrases across habitual, loud, and slow conditions. The primary dependent variable was proportion of words correct; follow-up acoustic analyses linked perceptual outcomes to changes in acoustic speech features.

RESULTS

Regardless of dysarthria type, the loud condition produced significant intelligibility gains. Overall, older listeners' comprehension was reduced relative to younger listeners. Follow-up analysis revealed considerable interspeaker differences in intelligibility outcomes across conditions. Although the most successful speaking mode varied, intelligibility gains were strongly associated with the degree of change participants made to their vowel formants.

CONCLUSIONS

Perceptual outcomes vary across speaking modes, even when speakers with dysarthria are grouped according to similar perceptual profiles. Further investigation of interspeaker differences is needed to inform individually tailored intervention approaches.

Assessing Vowel Centralization in Dysarthria: A Comparison of Methods

PURPOSE

The strength of the relationship between vowel centralization measures and perceptual ratings of dysarthria severity has varied considerably across reports. This article evaluates methods of acoustic-perceptual analysis to determine whether procedural changes can strengthen the association between these measures.

METHOD

Sixty-one speakers (17 healthy individuals and 44 speakers with dysarthria) read a standard passage. To obtain acoustic data, 2 points of formant extraction (midpoint and articulatory point) and 2 frequency measures (Hz and Bark) were trialed. Both vowel space area and an adapted formant centralization ratio were calculated using first and second formants of speakers' corner vowels. Twenty-eight listeners rated speech samples using different prompts: one with a focus on intelligibility, the other on speech precision.

RESULTS

Perceptually, listener ratings of speech precision provided the best index of acoustic change. Acoustically, the combined use of an articulatory-based formant extraction point, Bark frequency units, and the formant centralization ratio was most effective in explaining perceptual ratings. This combination of procedures resulted in an increase of 17% to 27% explained variance between measures.

CONCLUSIONS

The procedures researchers use to assess articulatory impairment can significantly alter the strength of relationship between acoustic and perceptual measures. Procedures that maximize this relationship are recommended.

The relationship between speech segment duration and vowel centralization in a group of older speakers

This study examined the relationship between average vowel duration and spectral vowel quality across a group of 149 New Zealand English speakers aged 65 to 90 yr. The primary intent was to determine whether participants who had a natural tendency to speak slowly would also produce more spectrally distinct vowel segments. As a secondary aim, this study investigated whether advancing age exhibited a measurable effect on vowel quality and vowel durations within the group. In examining vowel quality, both flexible and static formant extraction points were compared. Two formant measurements, from selected [ɐ:], [ i:], and [ o:] vowels, were extracted from a standard passage and used to calculate two measurements of vowel space area (VSA) for each speaker. Average vowel duration was calculated from segments across the passage. The study found a statistically significant relationship between speakers' average vowel durations and VSA measurements indicating that, on average, speakers with slower speech rates produced more acoustically distinct speech segments. As expected, increases in average vowel duration were found with advancing age. However, speakers' formant values remained unchanged. It is suggested that the use of a habitually slower speaking rate may assist speakers in maintaining acoustically distinct vowels.

Cognitive-perceptual examination of remediation approaches to hypokinetic dysarthria

PURPOSE

To determine how increased vocal loudness and reduced speech rate affect listeners' cognitive-perceptual processing of hypokinetic dysarthric speech associated with Parkinson's disease.

METHOD

Fifty-one healthy listener participants completed a speech perception experiment. Listeners repeated phrases produced by 5 individuals with dysarthria across habitual, loud, and slow speaking modes. Listeners were allocated to habitual ( n = 17), loud ( n = 17), or slow ( n = 17) experimental conditions. Transcripts derived from the phrase repetition task were coded for overall accuracy (i.e., intelligibility), and perceptual error analyses examined how these conditions affected listeners' phonemic mapping (i.e., syllable resemblance) and lexical segmentation (i.e., lexical boundary error analysis).

RESULTS

Both speech conditions provided obvious perceptual benefits to listeners. Overall, transcript accuracy was highest in the slow condition. In the loud condition, however, improvement was evidenced across the experiment. An error analysis suggested that listeners in the loud condition prioritized acoustic-phonetic cues in their attempts to resolve the degraded signal, whereas those in the slow condition appeared to preferentially weight lexical stress cues.

CONCLUSIONS

Increased loudness and reduced rate exhibited differential effects on listeners' perceptual processing of dysarthric speech. The current study highlights the insights that may be gained from a cognitive-perceptual approach.

A differential item functioning (DIF) analysis of the Communicative Participation Item Bank (CPIB): comparing individuals with Parkinson's disease from the United States and New Zealand

PURPOSE

To examine the cross-cultural applicability of the Communicative Participation Item Bank (CPIB) through a comparison of respondents with Parkinson's disease (PD) from the United States and New Zealand.

METHOD

A total of 428 respondents-218 from the United States and 210 from New Zealand-completed the self-report CPIB and a series of demographic questions. Differential item functioning (DIF) analyses were conducted to examine whether response bias was present across the 2 groups.

RESULTS

No items were identified as having statistically significant DIF across the U.S. and N.Z. cohorts.

CONCLUSION

The current CPIB items and scoring parameters are also suitable for use with respondents from New Zealand.

Vocabulary influences older and younger listeners' processing of dysarthric speech

This study examined younger (n = 16) and older (n = 16) listeners' processing of dysarthric speech-a naturally occurring form of signal degradation. It aimed to determine how age, hearing acuity, memory, and vocabulary knowledge interacted in speech recognition and lexical segmentation. Listener transcripts were coded for accuracy and pattern of lexical boundary errors. For younger listeners, transcription accuracy was predicted by receptive vocabulary. For older listeners, this same effect existed but was moderated by pure-tone hearing thresholds. While both groups employed syllabic stress cues to inform lexical segmentation, older listeners were less reliant on this perceptual strategy. The results were interpreted to suggest that individuals with larger receptive vocabularies, with their presumed greater language familiarity, were better able to leverage cue redundancies within the speech signal to form lexical hypothesis-leading to an improved ability to comprehend dysarthric speech. This advantage was minimized as hearing thresholds increased. While the differing levels of reliance on stress cues across the listener groups could not be attributed to specific individual differences, it was hypothesized that some combination of larger vocabularies and reduced hearing thresholds in the older participant group led to them prioritize lexical cues as a segmentation frame.

The role of linguistic and indexical information in improved recognition of dysarthric speech

This investigation examined perceptual learning of dysarthric speech. Forty listeners were randomly assigned to one of two identification training tasks, aimed at highlighting either the linguistic (word identification task) or indexical (speaker identification task) properties of the neurologically degraded signal. Twenty additional listeners served as a control group, passively exposed to the training stimuli. Immediately following exposure to dysarthric speech, all three listener groups completed an identical phrase transcription task. Analysis of listener transcripts revealed remarkably similar intelligibility improvements for listeners trained to attend to either the linguistic or the indexical properties of the signal. Perceptual learning effects were also evaluated with regards to underlying error patterns indicative of segmental and suprasegmental processing. The findings of this study suggest that elements within both the linguistic and indexical properties of the dysarthric signal are learnable and interact to promote improved processing of this type and severity of speech degradation. Thus, the current study extends support for the development of a model of perceptual processing in which the learning of indexical properties is encoded and retained in conjunction with linguistic properties of the signal.