Robert M. Kroll

Functional neuroimaging of cerebellar activation during single word reading and verb generation in stuttering and nonstuttering adults

Articulatory discoordinations typically observed in fluent and disfluent speech of stuttering adults suggest an underlying deficiency in the precise timing needed for speech production. Positron emission tomography scans of stuttering adults showed generally higher cerebellar activations pre-treatment compared to nonstuttering control subjects. Intensive fluency treatment resulted in increased cerebellar activation during reading immediately post-treatment and a decrease to near normal levels at the 1 year follow scan. In contrast, verb generation resulted in a gradual but consistent decrease over the three scans. The results suggest that automaticity in motor and cognitive processes during speech production may need to be considered as an important factor in future investigations of stuttering.

The effects of simulated stuttering and prolonged speech on the neural activation patterns of stuttering and nonstuttering adults.

Functional magnetic resonance imaging was used to investigate the neural correlates of passive listening, habitual speech and two modified speech patterns (simulated stuttering and prolonged speech) in stuttering and nonstuttering adults. Within-group comparisons revealed increased right hemisphere biased activation of speech-related regions during the simulated stuttered and prolonged speech tasks, relative to the habitual speech task, in the stuttering group. No significant activation differences were observed within the nonstuttering participants during these speech conditions. Between-group comparisons revealed less left superior temporal gyrus activation in stutterers during habitual speech and increased right inferior frontal gyrus activation during simulated stuttering relative to nonstutterers. Stutterers were also found to have increased activation in the left middle and superior temporal gyri and right insula, primary motor cortex and supplementary motor cortex during the passive listening condition relative to nonstutterers. The results provide further evidence for the presence of functional deficiencies underlying auditory processing, motor planning and execution in people who stutter, with these differences being affected by speech manner.

Relationship between speech motor control and speech intelligibility in children with speech sound disorders

UNLABELLED The current study was undertaken to investigate the impact of speech motor issues on the speech intelligibility of children with moderate to severe speech sound disorders (SSD) within the context of the PROMPT intervention approach. The word-level Childrens Speech Intelligibility Measure (CSIM), the sentence-level Beginners Intelligibility Test (BIT) and tests of speech motor control and articulation proficiency were administered to 12 children (3:11 to 6:7 years) before and after PROMPT therapy. PROMPT treatment was provided for 45 min twice a week for 8 weeks. Twenty-four naïve adult listeners aged 22-46 years judged the intelligibility of the words and sentences. For CSIM, each time a recorded word was played to the listeners they were asked to look at a list of 12 words (multiple-choice format) and circle the word while for BIT sentences, the listeners were asked to write down everything they heard. Words correctly circled (CSIM) or transcribed (BIT) were averaged across three naïve judges to calculate percentage speech intelligibility. Speech intelligibility at both the word and sentence level was significantly correlated with speech motor control, but not articulatory proficiency. Further, the severity of speech motor planning and sequencing issues may potentially be a limiting factor in connected speech intelligibility and highlights the need to target these issues early and directly in treatment. LEARNING OUTCOMES The reader will be able to: (1) outline the advantages and disadvantages of using word- and sentence-level speech intelligibility tests; (2) describe the impact of speech motor control and articulatory proficiency on speech intelligibility; and (3) describe how speech motor control and speech intelligibility data may provide critical information to aid treatment planning.

Treatment intensity and childhood apraxia of speech

BACKGROUND Intensive treatment has been repeatedly recommended for the treatment of speech deficits in childhood apraxia of speech (CAS). However, differences in treatment outcomes as a function of treatment intensity have not been systematically studied in this population. AIM To investigate the effects of treatment intensity on outcome measures related to articulation, functional communication and speech intelligibility for children with CAS undergoing individual motor speech intervention. METHODS & PROCEDURES A total of 37 children (32-54 months of age) with CAS received 1×/week (lower intensity) or 2×/week (higher intensity) individual motor speech treatment for 10 weeks. Assessments were carried out before and after a 10-week treatment block to study the effects of variations in treatment intensity on the outcome measures. OUTCOMES & RESULTS The results indicated that only higher intensity treatment (2×/week) led to significantly better outcomes for articulation and functional communication compared with 1×/week (lower intensity) intervention. Further, neither lower nor higher intensity treatment yielded a significant change for speech intelligibility at the word or sentence level. In general, effect sizes for the higher intensity treatment groups were larger for most variables compared with the lower intensity treatment group. CONCLUSIONS & IMPLICATIONS Overall, the results of the current study may allow for modification of service delivery and facilitate the development of an evidence-based care pathway for children with CAS.

Motor speech treatment protocol for developmental motor speech disorders

Abstract Objective: This study examines the effect of the Motor Speech Treatment Protocol (MSTP), a multi-sensory hybrid treatment approach on five children (mean: 3;3 years; S.D. 0;1) with severe to profound speech sound disorders with motor speech difficulties. Methods: A multiple probe design, replicated over five participants, was used to evaluate the effects of treatment on improving listeners’ auditory and visual judgements of speech accuracy. Results: All participants demonstrated significant change between baseline and maintenance conditions, with the exception of KM, who may have had underlying psychosocial, regulation and/or attention difficulties. The training- (practiced in treatment) and test-words (not practiced in treatment) both demonstrated positive change in all participants, indicating generalization of target features to untrained words. Conclusion: These results provide preliminary evidence that the MSTP, which integrates multi-sensory information and utilizes hierarchical goal selection, may positively impact speech sound production by improving speech motor control in this population.

Response latency and response class for stutterers and nonstutterers as measured by a word-association task

Abstract The present study investigated the response latency and response class characteristics of stutterers as measured by a word-association task. The hypothesis was that response latency would be significantly shorter for stutterers than for nonstutterers and that stutterers would produce significantly more paradigmatic class words than would nonstutterers. Fifteen adult stutterers and their matched controls were administered the Goldfarb-Halpern Word-Association Test, a list of 36 words balanced according to frequency of occurrence, length, level of abstraction, and grammatical class. Subject responses were classified as either paradigmatic or syntagmatic. Response latencies were calculated using the MacSpeech software program. No significant differences were found between groups on either response latency or response class measures. The clinical usefulness of the word-association task as a means of objectively examining avoidance behavior in stutterers is therefore regarded as limited. Also noteworthy was the finding that the stutterers were a highly heterogeneous group. The experimental group was found to be highly variable both in terms of the time it took them to produce a word-association response and also in the type of response given. The authors recommend continued inclusion of individual data in future research.

Changes in voice onset time and motor speech skills in children following motor speech therapy: Evidence from /pa/ productions

Abstract This study evaluated changes in motor speech control and inter-gestural coordination for children with speech sound disorders (SSD) subsequent to Prompts for Restructuring Oral and Muscular Phonetic Targets (PROMPT) intervention. We measured the distribution patterns of voice onset time (VOT) for a voiceless stop (/p/) to examine the changes in inter-gestural coordination. Two standardized tests were used (Verbal Motor Production Assessment for Children (VMPAC), GFTA-2) to assess the changes in motor speech skills and articulation. Data showed positive changes in patterns of VOT with a lower pattern of variability. All children showed significantly higher scores for VMPAC, but only some children showed higher scores for GFTA-2. Results suggest that the proprioceptive feedback provided through PROMPT had a positive influence on speech motor control and inter-gestural coordination in voicing behavior. This set of VOT data for children with SSD adds to our understanding of the speech characteristics underlying speech motor control. Directions for future studies are discussed.

The influence of task presentation and information load on the adaptation effect in stutterers and normal speakers

Fourteen stutterers and 14 normal speakers read two passages differing in information value under two different conditions. Condition I provided subjects with a priori knowledge regarding the experimental limits and requirements. Condition II withheld such knowledge. Results indicate that adaptation curves for both stutterers and normal speakers were influenced by the information value of the reading passage. Less adaptation was observed with the high information than with the low information passage. The task presentation variable differentiated stutterers from normal speakers. When a priori instructions were provided to stutterers, the adaptation curve assumed a smooth, decelerating course. When a priori instructions were withheld, the curve deviated from the expected course. For normal speakers, identical adaptation trends were observed whether or not a priori instructions were provided. Stuttering adaptation is a function of both linguistic and situational variables; normal nonfluency adaptation is primarily a function of linguistic variables. Theoretical, experimental, and clinical implications are offered.

Molecular self-analyses of stuttered speech via speech time expansion

Abstract The current investigation attempted to determine if a standard procedure could be utilized for training 40 naive adult stutterers to perform a molecular rather than molar self-analysis using speech time expanded recordings. All subjects provided a 3-min spontaneous speech sample from memory drum stimuli and two 100-word oral reading passages. Initial descriptive statements pertaining to the speech patterns were obtained from all subjects. Subjects were then systematically trained to identify each specific form of disfluency observed in their maladaptive speech patterns, including part word repetitions, interjections, whole word repetitions, prolongations, and hard contacts. Results of the training procedure indicated that the subjects as a group could be trained to reliably identify part word repetitions, prolongations, and interjections at the p

Clinician's molar and molecular stuttering analyses of expanded and nonexpanded speech

Abstract Twenty speech pathologists measured total words and completed molar and molecular stuttering analyses from audio-recorded contrived samples of stuttered speech. Each subject completed a criterion referenced test prior to performing the experimental tasks. Analyses were performed under two conditions: Condition I consisted of samples presented at 100 wpm as recorded (nonexpanded); Condition II consisted of parallel samples recorded at 100 wpm as recorded (nonexpanded condition); Condition II consisted of parallel samples recorded at 100 wpm but presented at 59 wpm via a speech time expander. Results indicate that presentation of expanded samples (Condition II) significantly increased subject accuracy for the specific disfluency form-types word repetitions and part-word repetitions. Similar trends were noted for sound prolongations and hard contacts. Theoretical, experimental, and clinical implications are offered.