Acoustic and Perceptual Consequences of Speech Cues for Children With Dysarthria

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.

Revisiting Dysarthria Treatment Across Languages: The Hybrid Approach

PURPOSE

Ten years after Miller and Lowit's (2014) groundbreaking book providing a cross-linguistic perspective on motor speech disorders, we ask where we are regarding dysarthria treatment across languages in two specific populations: adults with Parkinson's disease (PD) and children with cerebral palsy (CP).

METHOD

In this commentary, we consider preliminary evidence for both language-independent and language-specific approaches to treatment and propose a hybrid approach to speech treatment across languages, centered on the individual with dysarthria who speaks any given language.

CONCLUSIONS

Treatment research on individuals with dysarthria secondary to PD and CP is advancing, but several areas remain to be explored. Next steps are suggested for addressing the paucity and complexity of cross-linguistic speech treatment research.

Feedback From Automatic Speech Recognition to Elicit Clear Speech in Healthy Speakers

PURPOSE

This study assessed the effectiveness of feedback generated by automatic speech recognition (ASR) for eliciting clear speech from young, healthy individuals. As a preliminary step toward exploring a novel method for eliciting clear speech in patients with dysarthria, we investigated the effects of ASR feedback in healthy controls. If successful, ASR feedback has the potential to facilitate independent, at-home clear speech practice.

METHOD

Twenty-three healthy control speakers (ages 23-40 years) read sentences aloud in three speaking modes: Habitual, Clear (over-enunciated), and in response to ASR feedback (ASR). In the ASR condition, we used Mozilla DeepSpeech to transcribe speech samples and provide participants with a value indicating the accuracy of the ASR's transcription. For speakers who achieved sufficiently high ASR accuracy, noise was added to their speech at a participant-specific signal-to-noise ratio to ensure that each participant had to over-enunciate to achieve high ASR accuracy.

RESULTS

Compared to habitual speech, speech produced in the ASR and Clear conditions was clearer, as rated by speech-language pathologists, and more intelligible, per speech-language pathologist transcriptions. Speech in the Clear and ASR conditions aligned on several acoustic measures, particularly those associated with increased vowel distinctiveness and decreased speaking rate. However, ASR accuracy, intelligibility, and clarity were each correlated with different speech features, which may have implications for how people change their speech for ASR feedback.

CONCLUSIONS

ASR successfully elicited outcomes similar to clear speech in healthy speakers. Future work should investigate its efficacy in eliciting clear speech in people with dysarthria.

Rate Modulation Abilities in Acquired Motor Speech Disorders

PURPOSE

The purpose of this study was to describe, compare, and understand speech modulation capabilities of patients with varying motor speech disorders (MSDs) in a paradigm in which patients made highly cued attempts to speak faster or slower.

METHOD

Twenty-nine patients, 12 with apraxia of speech (AOS; four phonetic and eight prosodic subtype), eight with dysarthria (six hypokinetic and two spastic subtype), and nine patients without any neurogenic MSD completed a standard motor speech evaluation where they were asked to repeat words and sentences, which served as their "natural" speaking rate. They were then asked to repeat lower complexity (counting 1-5; repeating "cat" and "catnip" 3 times each) and higher complexity stimuli (repeating "catastrophe" and "stethoscope" 3 times each and "My physician wrote out a prescription" once) as fast/slow as possible. Word durations and interword intervals were measured. Linear mixed-effects models were used to assess differences related to MSD subtype and stimuli complexity on bidirectional rate modulation capacity as indexed by word duration and interword interval. Articulatory accuracy was also judged and compared.

RESULTS

Patients with prosodic AOS demonstrated a reduced ability to go faster; while they performed similarly to patients with spastic dysarthria when counting, patients with spastic dysarthria were able to increase rate similar to controls during sentence repetition; patients with prosodic AOS could not and made increased articulatory errors attempting to increase rate. AOS patients made more articulatory errors relative to other groups, regardless of condition; however, their percentage of errors reduced with an intentionally slowed speaking rate.

CONCLUSIONS

The findings suggest comparative rate modulation abilities in conjunction with their impact on articulatory accuracy may support differential diagnosis between healthy and abnormal speech and among subtypes of MSDs (i.e., type of dysarthria or AOS). Findings need to be validated in a larger, more representative cohort encompassing several types of MSDs.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.22044632.

Singing and Speaking Ability in Parkinson's Disease and Spinocerebellar Ataxia

PURPOSE

This study examined spontaneous, spoken-to-a-model, and two sung modes in speakers with Parkinson's disease (PD), speakers with cerebellar disease (CD), and healthy controls. Vocal performance was measured by intelligibility scores and listeners' perceptual ratings.

METHOD

Participants included speakers with hypokinetic dysarthria secondary to PD, those with ataxic dysarthria secondary to CD, and healthy speakers. Participants produced utterances in four vocal modes: spontaneous speech, spoken-to-a-model, sung-to-a-model, and spontaneous singing. For spoken-to-a-model and sung-to-a-model modes, written material was provided the model. For spontaneous singing, participants sang songs that they endorsed as familiar.

DEPENDENT VARIABLES

In Experiment I, listeners orthographically transcribed the audio samples of the first three vocal modes. In Experiment IIa, raters evaluated the accuracy of the pitch and rhythm of the spontaneous singing of familiar songs. Finally, familiar songs and sung-to-a-model utterances were rated on a competency scale by a second group of raters (Experiment IIb).

RESULTS

Results showed increases in intelligibility during the spoken-to-a-model mode compared with the spontaneous mode in both PD and CD groups. Singing enhanced the vocal output of speakers with PD more than in speakers with CD, as measured by percent intelligibility. PD participants' pitch and rhythm accuracy and competency in singing familiar songs was rated more favorably than those produced by CD participants.

CONCLUSIONS

The findings reveal a vocal task effect for spoken utterances in both groups. Sung exemplars, more impaired in CD, suggest a significant involvement of the cerebellum in singing.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21809544.

An Acoustic-Phonetic Approach to Effects of Face Masks on Speech Intelligibility

PURPOSE

This study aimed to examine the effects of wearing a face mask on speech acoustics and intelligibility, using an acoustic-phonetic analysis of speech. In addition, the effects of speakers' behavioral modification while wearing a mask were examined.

METHOD

Fourteen female adults were asked to read a set of words and sentences under three conditions: (a) conversational, mask-off; (b) conversational, mask-on; and (c) clear, mask-on. Seventy listeners rated speech intelligibility using two methods: orthographic transcription and visual analog scale (VAS). Acoustic measures for vowels included duration, first (F1) and second (F2) formant frequency, and intensity ratio of F1/F2. For consonants, spectral moment coefficients and consonant-vowel (CV) boundary (intensity ratio between consonant and vowel) were measured.

RESULTS

Face masks had a negative impact on speech intelligibility as measured by both intelligibility ratings. However, speech intelligibility was recovered in the clear speech condition for VAS but not for transcription scores. Analysis of orthographic transcription showed that listeners tended to frequently confuse consonants (particularly fricatives, affricates, and stops), rather than vowels in the word-initial position. Acoustic data indicated a significant effect of condition on CV intensity ratio only.

CONCLUSIONS

Our data demonstrate a negative effect of face masks on speech intelligibility, mainly affecting consonants. However, intelligibility can be enhanced by speaking clearly, likely driven by prosodic alterations.

Intelligibility, Speech Rate, and Communication Efficiency in Children With Neurological Conditions: A Longitudinal Study of Childhood Dysarthria

PURPOSE

This study aimed to describe communication-related parameters (i.e., intelligibility, speech rate, and communication efficiency) and their developmental courses in children with neurological conditions against the background of typical development. In addition, interrelations between the developmental courses of communication-related parameters and auditory-perceptual ratings related to speech subsystems were investigated.

METHOD

Fourteen children with neurological conditions (CNC) and 14 typically developing children (CTD), matched for age and gender (four girls; 5;1-8;4 [years;months] at first examination), were assessed at three points in time over an 18-month period. Speech samples were collected using the Bogenhausener Dysarthrie Skalen-Kindliche Dysarthrien (English: Bogenhausen Dysarthria Scales-Childhood Dysarthria), a German tool for the assessment of childhood dysarthria. To assess intelligibility, naïve listeners transcribed audio samples of sentence repetitions of the children. Speech rate was measured by acoustic analyses, and communication efficiency was determined by multiplying the proportion of correctly transcribed syllables with speech rate. Age normalization was performed following a recently published approach.

RESULTS

On the group level, CNC had conspicuous raw and normalized scores for the three communication-related parameters and were more variable than the CTD group regarding their developmental courses. These differences were more pronounced for intelligibility than for speech rate. A strong relationship between communication-related and speech subsystems-related auditory-perceptual characteristics was apparent only between intelligibility and articulation/resonance.

CONCLUSIONS

For the first time, age-normalized scores for communication-related parameters were reported in children with neurological disorders and put into a developmental context within the framework of a longitudinal study. Age-normalized intelligibility was more vulnerable to large developmental changes than speech rate and was best predicted by changes in articulation and resonance. Overall, this study may contribute to a more comprehensive and valid clinical assessment of childhood dysarthria and to a better understanding of its developmental dynamics.

Speech treatment for Hebrew-speaking adolescents and young adults with developmental dysarthria: A comparison of mSIT and Beatalk

BACKGROUND

Individuals with developmental dysarthria typically demonstrate reduced functioning of one or more of the speech subsystems, which negatively impacts speech intelligibility and communication within social contexts. A few treatment approaches are available for improving speech production and intelligibility among individuals with developmental dysarthria. However, these approaches have only limited application and research findings among adolescents and young adults.

AIMS

To determine and compare the effectiveness of two treatment approaches, the modified Speech Intelligibility Treatment (mSIT) and the Beatalk technique, on speech production and intelligibility among Hebrew-speaking adolescents and young adults with developmental dysarthria.

METHODS & PROCEDURES

Two matched groups of adolescents and young adults with developmental dysarthria participated in the study. Each received one of the two treatments, mSIT or Beatalk, over the course of 9 weeks. Measures of speech intelligibility, articulatory accuracy, voice and vowel acoustics were assessed both pre- and post-treatment.

OUTCOMES & RESULTS

Both the mSIT and Beatalk groups demonstrated gains in at least some of the outcome measures. Participants in the mSIT group exhibited improvement in speech intelligibility and voice measures, while participants in the Beatalk group demonstrated increased articulatory accuracy and gains in voice measures from pre- to post-treatment. Significant increases were noted post-treatment for first formant values for select vowels.

CONCLUSIONS & IMPLICATIONS

Results of this preliminary study are promising for both treatment approaches. The differentiated results indicate their distinct application to speech intelligibility deficits. The current findings also hold clinical significance for treatment among adolescents and young adults with motor speech disorders and application for a language other than English.

WHAT THIS PAPER ADDS

What is already known on the subject Developmental dysarthria (e.g., secondary to cerebral palsy) is a motor speech disorder that negatively impacts speech intelligibility, and thus communication participation. Select treatment approaches are available with the aim of improving speech intelligibility in individuals with developmental dysarthria; however, these approaches are limited in number and have only seldomly been applied specifically to adolescents and young adults. What this paper adds to existing knowledge The current study presents preliminary data regarding two treatment approaches, the mSIT and Beatalk technique, administered to Hebrew-speaking adolescents and young adults with developmental dysarthria in a group setting. Results demonstrate the initial effectiveness of the treatment approaches, with different gains noted for each approach across speech and voice domains. What are the potential or actual clinical implications of this work? The findings add to the existing literature on potential treatment approaches aiming to improve speech production and intelligibility among individuals with developmental dysarthria. The presented approaches also show promise for group-based treatments as well as the potential for improvement among adolescents and young adults with motor speech disorders.

Positive effects of the Beatalk technique on speech characteristics of young adults with intellectual disability

Background: The Beatalk technique is a speech therapy method, based on human beatboxing, involving intense, rapid repetitions of speech-like sounds. The goals of the current feasibility study were to test its effect in enhancing articulation accuracy and voice measures in a small group of adults with intellectual disability (ID), using a wide range of measures of verbal communication, and to refine the treatment protocol. Methods: A group pre-test-post-test experimental design was used (n = 12). Treatment consisted of ten weekly group sessions of 40 min, each followed by two self-practice sessions. Changes in speech intelligibility, voice, and communication skills were assessed. Results: The findings indicate significant improvements in speech production and intelligibility measures (Percentage of Consonant Correct, and staff-member intelligibility scores), voice measures (vocal loudness, Harmonic-Noise-Ratio, shimmer, and jitter) and staff-member communication scores. Implications: These results extend our understanding of the effects of the Beatalk technique, and suggest that it may have potential as an effective intervention for adults with ID. As the experimental design is limited in its ability to yield strong conclusions, further controlled studies are required.

Improving speech characteristics of young adults with congenital dysarthria: An exploratory study comparing articulation training and the Beatalk method

INTRODUCTION

This exploratory study compared the effects of two speech therapy approaches on speech characteristics of young adults with congenital dysarthria resulting from various etiologies: a) articulation training focusing on consonant articulation exercises at various levels (isolation, syllables, and words), and b) the Beatalk method, based on human beatboxing, i.e., producing various instrumental sounds in an a-cappella musical context. Both interventions were designed to increase participants' speech intelligibility.

METHODS

Twelve adults with congenital dysarthria and reduced speech intelligibility participated in treatment groups for eight weeks. Six participants were assigned to the articulation training group, and six to the Beatalk group. Intelligibility of single words and continuous speech, voice measures, and oral-diadochokinesis rates were measured before and after the treatment.

RESULTS

The results showed that the Beatalk intervention yielded a significant overall pre- to post-treatment effect. Specifically, it resulted in gains in articulatory accuracy and intelligibility for single words. Improvements were not noted following articulation training.

CONCLUSIONS

The results present initial evidence of the positive effect of the Beatalk method as an intervention tool for adults with congenital dysarthria. This relatively easy-to-learn technique shows promise, as it involves intense and repetitive production of speech sounds while controlling rhythm and breathing in an enjoyable context.

Inteligibilidad: diferentes perspectivas de su concepto y evaluación. Una revisión sistemática

Una adecuada inteligibilidad es un indicador del éxito en la comunicación. Su interferencia, a causa de cualquier patología, debe ser abordada en los objetivos primordiales de la terapia. No obstante, los métodos para su evaluación son poco conocidos. Objetivo: desarrollar una revisión sistemática que describa los métodos empleados en la medición de la inteligibilidad y discutir la conceptualización de este constructo. Metodología: se realiza una búsqueda en las bases de datos PubMed, ScieLo y Science Direct para identificar artículos publicados entre 1990 y 2018. Análisis y discusiones: Se seleccionan 50 investigaciones en inglés, español y portugués, que mostraron preferencia por medidas objetivas de evaluación, por sobre las medidas subjetivas de escala. La inteligibilidad se define mejor como un constructo dependiente de la señal acústica, a diferencia del concepto de comprensibilidad. Esta revisión ofrece información actualizada y organizada para optimizar procedimientos clínicos y científicos de medición de la inteligibilidad. 

Reliability of Perceptual Judgments of Phonetic Accuracy and Hypernasality Among Speech-Language Pathologists for Children With Dysarthria

Purpose The objectives of this study were to: (a) compare interrater reliability of practicing speech-language pathologists' (SLPs) perceptual judgments of phonetic accuracy and hypernasality between children with dysarthria and those with typical development, and (b) to identify speech factors that influence reliability of these perceptual judgments for children with dysarthria. Method Ten SLPs provided ratings of speech samples from twenty 5-year-old children with dysarthria and twenty 5-year-old children with typical development on two tasks via a web-based platform: a hypernasality judgment task and a phonetic accuracy judgment task. Interrater reliability of SLPs' ratings on both tasks was compared between children with dysarthria and children with typical development. For children with dysarthria, four acoustic speech measures, intelligibility, and a measure of phonetic accuracy (percent stops correct) were examined as predictors of reliability of SLPs' perceptual judgments. Results Reliability of SLPs' phonetic accuracy judgments and hypernasality ratings was significantly lower for children with dysarthria than for children with typical development. Among children with dysarthria, interrater reliability of perceptual judgments ranged from strong to weak. Percent stops correct was the strongest predictor of interrater reliability for both phonetic accuracy judgments and hypernasality ratings. Conclusions Reliability of perceptual phonetic accuracy judgments and hypernasality ratings among practicing SLPs for children with dysarthria is reduced compared to ratings for children with typical development. Findings underscore the need for more reliable methods to assess phonetic accuracy and hypernasality for children with dysarthria.

Speech Treatment Effects on Narrative Intelligibility in French-Speaking Children With Dysarthria

Purpose This study examined the effects of Speech Intelligibility Treatment (SIT) on intelligibility and naturalness of narrative speech produced by francophone children with dysarthria due to cerebral palsy. Method Ten francophone children with dysarthria were randomized to one of two treatments, SIT or Hand-Arm Bimanual Intensive Therapy Including Lower Extremities, a physical therapy (PT) treatment. Both treatments were conducted in a camp setting and were comparable in dosage. The children were recorded pre- and posttreatment producing a story narrative. Intelligibility was measured by means of 60 blinded listeners' orthographic transcription accuracy (percentage of words transcribed correctly). The listeners also rated the children's naturalness on a visual analogue scale. Results A significant pre- to posttreatment increase in intelligibility was found for the SIT group, but not for the PT group, with great individual variability observed among the children. No significant changes were found for naturalness ratings or sound pressure level in the SIT group or the PT group posttreatment. Articulation rate increased in both treatment groups, although not differentially across treatments. Conclusions Findings from this first treatment study on intelligibility in francophone children with dysarthria suggest that SIT shows promise for increasing narrative intelligibility in this population. Acoustic contributors to the increased intelligibility remain to be explored further. Supplemental Material https://doi.org/10.23641/asha.14161943.

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.

Effect of boost articulation therapy (BArT) on intelligibility in adults with dysarthria

BACKGROUND

The articulatory accuracy of patients with dysarthria is one of the most affected speech dimensions with a high impact on speech intelligibility. Behavioural treatments of articulation can either involve direct or indirect approaches. The latter have been thoroughly investigated and are generally appreciated for their almost immediate effects on articulation and intelligibility. The number of studies on (short-term) direct articulation therapy is limited.

AIMS

To investigate the effects of short-term, boost articulation therapy (BArT) on speech intelligibility in patients with chronic or progressive dysarthria and the effect of severity of dysarthria on the outcome.

METHODS & PROCEDURES

The study consists of a two-group pre-/post-test design to assess speech intelligibility at phoneme and sentence level and during spontaneous speech, automatic speech and reading a phonetically balanced text. A total of 17 subjects with mild to severe dysarthria participated in the study and were randomly assigned to either a patient-tailored, intensive articulatory drill programme or an intensive minimal pair training. Both training programmes were based on the principles of motor learning. Each training programme consisted of five sessions of 45 min completed within one week.

OUTCOMES & RESULTS

Following treatment, a statistically significant increase of mean group intelligibility was shown at phoneme and sentence level, and in automatic sequences. This was supported by an acoustic analysis that revealed a reduction in formant centralization ratio. Within specific groups of severity, large and moderate positive effect sizes with Cohen's d were demonstrated.

CONCLUSIONS & IMPLICATIONS

BArT successfully improves speech intelligibility in patients with chronic or progressive dysarthria at different levels of the impairment. What this paper adds What is already known on the subject Behavioural treatment of articulation in patients with dysarthria mainly involves indirect strategies, which have shown positive effects on speech intelligibility. However, there is limited evidence on the short-term effects of direct articulation therapy at the segmental level of speech. This study investigates the effectiveness of BArT on speech intelligibility in patients with chronic or progressive dysarthria at all severity levels. What this paper adds to existing knowledge The intensive and direct articulatory therapy programmes developed and applied in this study intend to reduce the impairment instead of compensating it. This approach results in a significant improvement of speech intelligibility at different dysarthria severity levels in a short period of time while contributing to exploit and develop all available residual motor skills in persons with dysarthria. What are the potential or actual clinical implications of this work? The improvements in intelligibility demonstrate the effectiveness of a BArT at the segmental level of speech. This makes it to be considered a suitable approach in the treatment of patients with chronic or progressive dysarthria.

Acoustic vowel analysis and speech intelligibility in young adult Hebrew speakers: Developmental dysarthria versus typical development

BACKGROUND

Developmental dysarthria is a motor speech impairment commonly characterized by varying levels of reduced speech intelligibility. The relationship between intelligibility deficits and acoustic vowel space among these individuals has long been noted in the literature, with evidence of vowel centralization (e.g., in English and Mandarin). However, the degree to which this centralization occurs and the intelligibility-acoustic relationship is maintained in different vowel systems has yet to be studied thoroughly. In comparison with American English, the Hebrew vowel system is significantly smaller, with a potentially smaller vowel space area, a factor that may impact upon the comparisons of the acoustic vowel space and its correlation with speech intelligibility. Data on vowel space and speech intelligibility are particularly limited for Hebrew speakers with motor speech disorders.

AIMS

To determine the nature and degree of vowel space centralization in Hebrew-speaking adolescents and young adults with dysarthria, in comparison with typically developing (TD) peers, and to correlate these findings with speech intelligibility scores.

METHODS & PROCEDURES

Adolescents and young adults with developmental dysarthria (secondary to cerebral palsy (CP) and other motor deficits, n = 17) and their TD peers (n = 17) were recorded producing Hebrew corner vowels within single words. For intelligibility assessments, naïve listeners transcribed those words produced by speakers with CP, and intelligibility scores were calculated.

OUTCOMES & RESULTS

Acoustic analysis of vowel formants (F1, F2) revealed a centralization of vowel space among speakers with CP for all acoustic metrics of vowel formants, and mainly for the formant centralization ratio (FCR), in comparison with TD peers. Intelligibility scores were correlated strongly with the FCR metric for speakers with CP.

CONCLUSIONS & IMPLICATIONS

The main results, vowel space centralization for speakers with CP in comparison with TD peers, echo previous cross-linguistic results. The correlation of acoustic results with speech intelligibility carries clinical implications. Taken together, the results contribute to better characterization of the speech production deficit in Hebrew speakers with motor speech disorders. Furthermore, they may guide clinical decision-making and intervention planning to improve speech intelligibility. What this paper adds What is already known on the subject Speech production and intelligibility deficits among individuals with developmental dysarthria (e.g., secondary to CP) are well documented. These deficits have also been correlated with centralization of the acoustic vowel space, although primarily in English speakers. Little is known about the acoustic characteristics of vowels in Hebrew speakers with motor speech disorders, and whether correlations with speech intelligibility are maintained. What this paper adds to existing knowledge This study is the first to describe the acoustic characteristics of vowel space in Hebrew-speaking adolescents and young adults with developmental dysarthria. The results demonstrate a centralization of the acoustic vowel space in comparison with TD peers for all measures, as found in other languages. Correlation between acoustic measures and speech intelligibility scores were also documented. We discuss these results within the context of cross-linguistic comparisons. What are the potential or actual clinical implications of this work? The results confirm the use of objective acoustic measures in the assessment of individuals with motor speech disorders, providing such data for Hebrew-speaking adolescents and young adults. These measures can be used to determine the nature and severity of the speech deficit across languages, may guide intervention planning, as well as measure the effectiveness of intelligibility-based treatment programmes.

Generalized Learning of Dysarthric Speech Between Male and Female Talkers

Purpose Perceptual training is a listener-targeted means for improving intelligibility of dysarthric speech. Recent work has shown that training with one talker generalizes to a novel talker of the same sex and that the magnitude of benefit is maximized when the talkers are perceptually similar. The current study expands previous findings by investigating whether perceptual training effects generalize between talkers of different sex. Method Forty new listeners were recruited for this study and completed a pretest, familiarization, and posttest perceptual training paradigm. Historical data collected using the same three-phase protocol were included in the data analysis. All listeners were exposed to the same talker with dysarthria during the pretest and posttest phases. For the familiarization phase, listeners were exposed to one of four talkers with dysarthria, differing in sex and level of perceptual similarity to the test talker or a control talker. During the testing phases, listener transcribed phrases produced by the test talker with dysarthria. Listener transcriptions were then used to calculate a percent words correct intelligibility score. Results Multiple linear regression analysis revealed that intelligibility at posttest was not predicted by sex of the training talker. Consistent with earlier work, the magnitude of intelligibility gain was greater when the familiarization and test talkers were perceptually similar. Additional analyses revealed greater between-listeners variability in the dissimilar conditions as compared to the similar conditions. Conclusions Learning as a result of perceptual training with one talker with dysarthria generalized to another talker regardless of sex. In addition, listeners trained with perceptually similar talkers had greater and more consistent intelligibility improvement. Together, these results add to previous evidence demonstrating that learning generalizes to novel talkers with dysarthria and that perceptual training is suitable for many listeners.

Neuromuscular and biomechanical adjustments of the speech mechanism during modulation of vocal loudness in children with cerebral palsy and dysarthria

ABSTRACChildren with cerebral palsy (CP) are characterized as difficult to understand because of poor articulation and breathy voice quality. This case series describes the subsystems of the speech mechanism (i.e., respiratory, laryngeal, oroarticulatory) in four children with CP and four matched typically developing children (TDC) during the modulation of vocal loudness. TDC used biomechanically efficient strategies among speech subsystems to increase vocal loudness. Children with CP made fewer breathing adjustments but recruited greater chest wall muscle activity and neuromuscular drive for louder productions. These results inform future clinical research and identify speech treatment targets for children with motor speech disorders.

Effects of speech cues in French-speaking children with dysarthria

BACKGROUND

Articulatory excursion and vocal intensity are reduced in many children with dysarthria due to cerebral palsy (CP), contributing to the children's intelligibility deficits and negatively affecting their social participation. However, the effects of speech-treatment strategies for improving intelligibility in this population are understudied, especially for children who speak languages other than English. In a cueing study on English-speaking children with dysarthria, acoustic variables and intelligibility improved when the children were provided with cues aimed to increase articulatory excursion and vocal intensity. While French is among the top 20 most spoken languages in the world, dysarthria and its management in French-speaking children are virtually unexplored areas of research. Information gleaned from such research is critical for providing an evidence base on which to provide treatment.

AIMS

To examine acoustic and perceptual changes in the speech of French-speaking children with dysarthria, who are provided with speech cues targeting greater articulatory excursion (French translation of 'speak with your big mouth') and vocal intensity (French translation of 'speak with your strong voice'). This study investigated whether, in response to the cues, the children would make acoustic changes and listeners would perceive the children's speech as more intelligible.

METHODS & PROCEDURES

Eleven children with dysarthria due to CP (six girls, five boys; ages 4;11-17;0 years; eight with spastic CP, three with dyskinetic CP) repeated pre-recorded speech stimuli across three speaking conditions (habitual, 'big mouth' and 'strong voice'). Stimuli were sentences and contrastive words in phrases. Acoustic analyses were conducted. A total of 66 Belgian-French listeners transcribed the children's utterances orthographically and rated their ease of understanding on a visual analogue scale at sentence and word levels.

OUTCOMES & RESULTS

Acoustic analyses revealed significantly longer duration in response to the big mouth cue at sentence level and in response to both the big mouth and strong voice cues at word level. Significantly higher vocal sound-pressure levels were found following both cues at sentence and word levels. Both cues elicited significantly higher first-formant vowel frequencies and listeners' greater ease-of-understanding ratings at word level. Increases in the percentage of words transcribed correctly and in sentence ease-of-understanding ratings, however, did not reach statistical significance. Considerable variability between children was observed.

CONCLUSIONS & IMPLICATIONS

Speech cues targeting greater articulatory excursion and vocal intensity yield significant acoustic changes in French-speaking children with dysarthria. However, the changes may only aid listeners' ease of understanding at word level. The significant findings and great inter-speaker variability are generally consistent with studies on English-speaking children with dysarthria, although changes appear more constrained in these French-speaking children. What this paper adds What is already known on the subject According to the only study comparing effects of speech-cueing strategies on English-speaking children with dysarthria, intelligibility increases when the children are provided with cues aimed to increase articulatory excursion and vocal intensity. Little is known about speech characteristics in French-speaking children with dysarthria and no published research has explored effects of cueing strategies in this population. What this paper adds to existing knowledge This paper is the first study to examine the effects of speech cues on the acoustics and intelligibility of French-speaking children with CP. It provides evidence that the children can make use of cues to modify their speech, although the changes may only aid listeners' ease of understanding at word level. What are the potential or actual clinical implications of this work? For clinicians, the findings suggest that speech cues emphasizing increasing articulatory excursion and vocal intensity show promise for improving the ease of understanding of words produced by francophone children with dysarthria, although improvements may be modest. The variability in the responses also suggests that this population may benefit from a combination of such cues to produce words that are easier to understand.

Vowel Acoustics and Speech Intelligibility in Young Adults With Down Syndrome

Purpose Speech production deficits and reduced intelligibility are frequently noted in individuals with Down syndrome (DS) and are attributed to a combination of several factors. This study reports acoustic data on vowel production in young adults with DS and relates these findings to perceptual analysis of speech intelligibility. Method Participants were eight young adults with DS as well as eight age- and gender-matched typically developing (TD) controls. Several different acoustic measures of vowel centralization and variability were applied to tokens of corner vowels (/ɑ/, /æ/, /i/, /u/) produced in common English words. Intelligibility was assessed for single-word productions of speakers with DS, by means of transcriptions from 14 adult listeners. Results Group differentiation was found for some, but not all, of the acoustic measures. Low vowels were more acoustically centralized and variable in speakers with DS than TD controls. Acoustic findings were associated with overall intelligibility scores. Vowel formant dispersion was the most sensitive measure in distinguishing DS and TD formant data. Conclusion Corner vowels are differentially affected in speakers with DS. The acoustic characterization of vowel production and its association with speech intelligibility scores within the DS group support the conclusion of motor control deficits in the overall speech impairment. Implications are discussed for effective treatment planning.

Effects of Rate Manipulation on Intelligibility in Children With Cerebral Palsy

Purpose We evaluated the effects of a speech supplementation strategy to reduce rate and improve intelligibility in children with cerebral palsy. Method Twenty-five children with cerebral palsy (M _age = 12.08 years) completed a structured speaking task in 2 speech conditions: habitual speech and slow speech. Fifteen children had mild intelligibility deficits; 10 had moderate-severe intelligibility deficits. In each condition, children repeated utterances of 2-7 words in length. In the habitual speech condition, children used their natural and unaltered speaking rate. In the slow speech condition, children were cued to insert pauses between words. Intelligibility ratings were obtained from orthographic transcriptions by unfamiliar adult listeners (n = 100). Speech rate, in words per minute, was measured for each utterance. Results All children, regardless of severity group, were able to reduce their rate of speech when implementing the slow speech strategy. Only children in the moderate-severe group showed an improvement in intelligibility when implementing the slow speech strategy. Although there was considerable individual variability, there was a greater improvement in intelligibility for longer utterances compared to shorter ones. Conclusion A slow speech strategy may be beneficial for children with moderate-severe intelligibility deficits who speak in longer utterances. Future studies should seek to further examine the clinical feasibility of slow speech for children with reduced intelligibility.

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.

Characteristics of Speech Rate in Children With Cerebral Palsy: A Longitudinal Study

PURPOSE

The purpose of this longitudinal study was to examine the effect of time and sentence length on speech rate and its characteristics, articulation rate and pauses, within 2 groups of children with cerebral palsy (CP).

METHOD

Thirty-four children with CP, 18 with no speech motor involvement and 16 with speech motor involvement, produced sentences of varying lengths at 3 time points that were 1 year apart (mean age = 56 months at first time point). Dependent measures included speech rate, articulation rate, proportion of time spent pausing, and average number and duration of pauses.

RESULTS

There were no significant effects of time. For children with no speech motor involvement, speech rate increased with longer sentences due to increased articulation rate. For children with speech motor involvement, speech rate did not change with sentence length due to significant increases in the proportion of time spent pausing and average number of pauses in longer sentences.

CONCLUSIONS

There were no significant age-related differences in speech rate in children with CP regardless of group membership. Sentence length differentially impacted speech rate and its characteristics in both groups of children with CP. This may be due to cognitive-linguistic and/or speech motor control factors.

Early Predictors and Correlates of Communication Function in Children With Cerebral Palsy

Birth characteristics and developmental milestones were evaluated as early predictors/correlates of communication in children with cerebral palsy. The hypothesis was that maternal report of child's age for vocal play and first words would predict current functional communication. A case series of 215 children, 2 to 17 years (mean age = 8.2 years, SD = 3.9) with cerebral palsy was recruited from medical practices in 3 Michigan cities. Early developmental data were collected by maternal interview. The child's Communication Function Classification System (CFCS) level was obtained from parent. Predictors of less functional communication included gestational age >32 weeks, number of comorbidities, age of first words after age 24 months, and use of communication methods other than speech. Several birth characteristics and developmental language milestones were predictive of later communication performance for children with cerebral palsy. These characteristics and milestones should trigger referrals for communication evaluations, including speech, language, hearing, and/or augmentative and alternative communication.

The Effects of Intensive Speech Treatment on Conversational Intelligibility in Spanish Speakers With Parkinson's Disease

PURPOSE

The purpose of this study was to examine the effects of intensive speech treatment on the conversational intelligibility of Castilian Spanish speakers with Parkinson's disease (PD), as well as on the speakers' self-perceptions of disability.

METHOD

Fifteen speakers with a medical diagnosis of PD participated in this study. Speech recordings were completed twice before treatment, immediately posttreatment, and at a 1-month follow-up session. Conversational intelligibility was assessed in 2 ways-transcription accuracy scores and intelligibility ratings on a 9-point Likert scale. The Voice Handicap Index (Núñez-Batalla et al., 2007) was administered as a measure of self-perceived disability.

RESULTS

Group data revealed that transcription accuracy and median ease-of-understanding ratings increased significantly immediately posttreatment, with gains maintained at the 1-month follow-up. The functional subscale of the Voice Handicap Index decreased significantly posttreatment, suggesting a decrease in perceived communication disability after speech treatment.

CONCLUSION

These findings support the implementation of intensive voice treatment to improve conversational intelligibility in Spanish speakers with PD with dysarthria as well as to improve the speakers' perception of their daily communicative capabilities. Clinical and theoretical considerations are discussed.