Linguistic aspects of stuttering: research updates on the language-fluency interface

Erasmus clinical model of the onset and development of stuttering 2.0

A clinical, evidence-based model to inform clients and their parents about the nature of stuttering is indispensable for the field. In this paper, we propose the Erasmus Clinical Model of Stuttering 2.0 for children who stutter and their parents, and adult clients. It provides an up-to-date, clinical model summary of current insights into the genetic, neurological, motoric, linguistic, sensory, temperamental, psychological and social factors (be it causal, eliciting, or maintaining) related to stuttering. First a review is presented of current insights in these factors, and of six scientific theories or models that have inspired the development of our current clinical model. Following this, we will propose the model, which has proven to be useful in clinical practice. The proposed Erasmus Clinical Model of Stuttering visualizes the onset and course of stuttering, and includes scales for stuttering severity and impact, to be completed by the (parent of) the person who stutters. The pathway of the model towards stuttering onset is based on predisposing and mediating factors. In most children with an onset of stuttering, stuttering is transient, but if stuttering continues, its severity and impact vary widely. The model includes the circle of Engel (1977), which visualizes unique interactions of relevant biological, psychological, and social factors that determine the speaker's experience of stuttering severity and its impact. Discussing these factors and their interaction with an individual client can feed into therapeutic targets. The model is supplemented by a lifeline casus.

Could linguistic and cognitive factors, degree of autistic traits and sex predict speech disfluencies in autistic young adults and controls?

This study aimed to evaluate the effect of linguistic complexity and individual background variables (i.e. linguistic and cognitive abilities, degree of autistic traits, and sex) on speech disfluencies in autistic young adults and controls. Thirty-two 19- to 33-year-old autistic adults and 35 controls participated in this study. The frequency of disfluencies and stuttering severity were evaluated based on a narrative speech task. Linguistic complexity was assessed by evaluating the syntactic structures of the narratives. Cognitive and linguistic abilities were assessed using the General Ability Index (GAI), Verbal Comprehension Index (VCI) and Perceptual Reasoning Index (PRI) from the Wechsler Adult Intelligence Scale IV. Autistic traits were measured using the Autism Spectrum Quotient (AQ). Multiple-linear regression analyses (syntactic complexity, GAI, AQ, sex, and group status as predictors) showed that (a) syntactic complexity predicted total and stuttering-like disfluencies and stuttering severity, (b) GAI predicted typical disfluencies, and (c) sex predicted total, typical, and stuttering-like disfluencies. Additional correlation analyses revealed negative association between PRI and disfluencies in the control group but not in the autistic group. No connection was found between AQ and disfluencies. It seems that while some connections between disfluencies and individual cognitive features were found, some of the possible contributing factors for greater speech disfluency might differ between autistic and typical speakers.

Disfluencies in the narratives of Russian-Hebrew bilingual children with and without Developmental Language Disorder (DLD)

The present study examined disfluencies in the narratives of Russian-Hebrew bilingual children with Developmental Language Disorder (DLD) and Typical Language Development (TLD) in both Russian (home language) and Hebrew (societal language), with a focus on the independent and combined effects of language disorder and cross-linguistic differences on the rates and loci of disfluencies. Narratives were collected from 44 bilingual children (14 with DLD), ages 5;7-6;6, using a story retelling procedure. The narrative coding system targeted ratios of the following disfluencies (per C-unit): silent pauses, repetitions, self-corrections, and filled pauses. Silent pauses longer than 0.25 sec were identified using PRAAT software© and were classified according to the following durations: more than 0.5 sec, 1 sec, 1.5 sec, and 2 sec. In addition, the loci of pauses (utterance-initial or utterance-internal) and repetitions (content or function words) were coded. Overall, children with DLD and TLD had comparable rates of disfluencies but differed for pauses longer than 0.5 sec and repetition of content words in both languages. For the overall ratio of pauses (more than 0.25 sec), children with and without DLD had more pauses in Russian. Long pauses and repetition of content words reflect difficulties for bilingual children with DLD in dealing with the demands of storytelling, in particular planning processes. A higher ratio of pauses in Russian suggests that they reflect lower proficiency in that language.

Communicative practices and perceptions towards stuttering people in South Africa

BACKGROUND

 A few studies have explored the life experiences of people who stutter. Research has shown that stuttering affects a significant number of people in the population.

OBJECTIVES

 The study was designed to explore the experiences of people who stutter and the perception of stuttering in South Africa.

METHOD

 Four people who identified as South Africans who stutter participated in this study. The primary investigator conducted semi-structured interviews with each of the participants. In addition, a questionnaire was administered to 20 acquaintances of all the participants. Transcriptions of interviews and results of questionnaires were analysed for major and minor themes.

RESULTS

 Results of this study suggest different perceptions by those who stutter and those acquainted with them. The findings of the study show that people who stutter experience communication barriers, so they adopt certain strategies to manage and cope with their speech disorder. The findings showed that stuttering has a pervasive impact on the lives of people who stutter and how they view themselves, considering negative societal views.

CONCLUSION

 Evaluation of the results from the study reveals that although stuttering is a common speech disorder, many people who are less informed about it harbour various stereotypes and myths that stigmatise stuttering. This study concludes by outlining recommendations for creating awareness of stuttering. It suggests vigorous campaigns aiming at promoting a multilevel approach that extends beyond the mere social and professional understanding of stuttering but addresses the inherent perceptions, myths, and stereotypes around stuttering.Contribution: Experiences of people who stutter and perceptions towards stuttering can help to better understand the speech disorder and overcome myths and stereotyping of stuttering.

A case study of bilingual neurogenic stuttering: Measures of fluency, emotion, and articulation rate

INTRODUCTION

This study explores the features of bilingual neurogenic stuttering and the potential connection between emotion and articulation rate on speech disfluencies.

METHOD

The participant is  a 59-year old, Yiddish-English bilingual male with a moderate non-fluent aphasia. Thirty-two narratives (16 in each language), elicited using cue words, were analyzed for frequency of disfluency, type of disfluency (stuttering vs. non-stuttering-like), word-type (content vs. function), within-word location of disfluency, and occurrence of accessory behaviors. Additionally, the percentage and type of emotion (positive vs. negative) expressed, and articulation rate (fluent syllables spoken/duration of fluent utterances) was assessed.

RESULTS

Disfluency occurred in each language with approximately equal frequency. The most common stuttering-like disfluencies were repetitions (monosyllabic, sound, and syllable) and prolongations. The most common non-stuttering-like disfluencies were self-correction/revisions, phrase and multisyllabic word repetitions, and pauses (silent and filled). In both languages, disfluencies occurred on both content and function words, but primarily content words, and in any position of the word, although primarily initial position. No accessory behaviors were noted. There was a similar amount of emotion words used in each language although the first acquired language, L1/Yiddish, had an overall more positive tone, and his second acquired language, L2/English, had a more negative tone. Additionally, there was a negative relationship between emotion and the number of disfluencies in L1/Yiddish, and a positive relationship in L2/English. A faster articulation rate was found in his native and more proficient language, Yiddish, than English. There was a negative relationship between articulation rate and the number of disfluencies in L1/Yiddish, and a positive relationship in L2/English.

CONCLUSIONS

Cross-linguistics differences for emotion and articulation rate demonstrates that these aspects impact on fluency and contributes to the disfluencies in each language. Clinical implications of the study demonstrates the importance of assessment of bilingual (i.e., proficiency and dominance) and fluency features of each language in the diagnostic process and the significance of considering emotional processes and articulation rate as part of a comprehensive intervention plan for acquired stuttering.

Reduced duration of stuttering-like disfluencies and consistent anticipatory slowing during an adaptation task

PURPOSE

The adaptation effect in stuttering, traditionally described as the reduction of stuttering moments over repeated readings, provides a context to investigate fluency facilitation as well as a relatively controlled means of comparing fluent speech in the immediate vicinity of words that were stuttered versus fluently produced. Acoustic studies have documented decreased duration of fluent speech during adaptation but rarely address changes in disfluencies or the speech preceding or following the disfluencies. This study addresses this gap in the research by documenting frequency and duration changes in both fluent and stuttered syllables.

METHOD

Fifteen people who stutter read passages aloud five times in succession. Frequency and duration of fluent syllables, pauses, stuttering-like disfluencies (SLDs) and other disfluencies (ODs) were compared across the five readings. In addition, durations for syllables before and after pauses and SLDs were compared to determine if there were anticipation or carryover effects of SLDs on surrounding syllables.

RESULTS

Durations measured for more than 22 000 fluent syllables, 1531 pauses, 128 ODs and 1752 SLDs. For most of the 15 participants, significant decreases in both frequency and duration of SLDs over the five readings were observed. In addition, lengthening of fluent syllables immediately preceding the disfluent syllables was observed: this pre-SLD lengthening did not change over the five readings.

CONCLUSIONS

Decreased duration of SLDs across readings supports the motor practice hypothesis, which assumes that successive reading of the same text increases the efficiency of the speech motor plans resulting in less stuttering and decreased durations of the stuttering that persists. Pre-SLD lengthening merits further study, because it informs our knowledge of the time course of stuttered events and may be associated with conscious or unconscious anticipation of upcoming SLDs that does not decrease with motor practice.

WHAT THIS PAPER ADDS

What is already known on this subject The frequency of stuttering-like disfluencies (SLDs) can be reduced using a variety of fluency-enhancing strategies. For example, the adaptation effect, in which a reduction of stuttered events occurs over repeated readings of the same material, has been widely studied. Previous studies have shown that durations of fluent syllables decrease during adaptation, supporting the hypothesis that repeated practice of the motor plan leads to increased fluency. However, temporal changes in disfluent syllables and syllables preceding and following SLDs have rarely been studied, so our understanding of the effect of motor practice on stuttering reduction is incomplete. What this study adds This study has two significant findings. First, stuttered disfluencies that persisted after the initial reading of the adaptation task tended to become shorter in duration. Fluently produced syllables and those that were stuttered, both of which are speech events related to motor control of articulators, were affected in a similar manner by the motor practice associated with adaptation. Second, lengthening of fluent syllables immediately preceding stuttered syllables was observed. This pre-stuttering lengthening, however, did not decrease in duration over the five readings: the mechanism that drives this anticipatory behaviour is not affected by repeated practice. What are the clinical implications of this work? People who stutter have neural differences that lead to speech motor planning and/or execution that is less efficient than that of typical speakers. The finding that stuttering is reduced and that persisting SLDs become shorter in duration over repeated readings provides evidence that motor practice can influence the manifestation of stuttering by temporarily making those specific motor plans more efficient. This may inform treatments for stuttering. The observation that fluent syllables immediately before SLDs were lengthened, and that this lengthening was not influenced by repeated practice, extends our understanding of the time course of stuttering events and may be useful in understanding anticipation and listener reactions to stuttering.

Statistical Information Affects Spoken Word Recognition of Tone Languages in Stutterers: Evidence From an Auditory-Perceptual Gating Study

PURPOSE

Previous studies have shown that individuals who stutter exhibit abnormal speech perception in addition to disfluent production as compared with their nonstuttering peers. This study investigated whether adult Chinese-speaking stutterers are still able to use knowledge of statistical regularities embedded in their native language to recognize spoken words and, if so, how much acoustic information is needed to trigger this information.

METHOD

Seventeen stutterers and 20 typical, nonstuttering controls participated in a gating experiment. All participants listened to monosyllabic words that consisted of syllables and lexical tones and were segmented into eight successive gates. These words differed in syllable token frequency and syllable-tone co-occurrence probability in line with a Chinese spoken word corpus. The correct syllable-only, correct tone-only, correct syllable-tone word, and correct syllable-incorrect tone responses were analyzed between the two groups using mixed-effects models.

RESULTS

Stutterers were less accurate overall than controls, with fewer correct syllables, tones, and their combination as words. However, stutterers showed consistent and reliable perceptual patterns triggered by statistical information of speech, as reflected by more accurate responses to high-frequency syllables, high-probability tones, and tone errors all in manners similar to those of nonstuttering controls.

CONCLUSIONS

Stutterers' atypical speech perception is not due to a lack of statistical learning. Stutterers were able to perceive spoken words with phonological tones based on statistical regularities embedded in their native speech. This finding echoes previous production studies of stuttering and lends some support for a link between perception and production. Implications of pathological, diagnostic, and therapeutic conditions of stuttering are discussed.

Bilingualism as a risk factor for false reports of stuttering in the Early Childhood Longitudinal Study (ECLS-K:2011)

Introduction

Bilingualism has historically been claimed to be a risk factor for developmental stuttering. The Early Childhood Longitudinal Study, Kindergarten Class of 2010-11 (ECLS-K:2011) ostensibly contains evidence to test that claim.

Methods

We analyze data from monolingual and bilingual children in Kindergarten through fifth grade in the ECLS-K:2011.

Results and discussion

The prevalence, male/female ratio, and onset and recovery of reported stuttering in the ECLS are inconsistent with widely-accepted clinical reports of stuttering. We argue that the reported figures may be misleading. We discuss some factors that may inflate the reported prevalence, including a lack of awareness of the difference between stuttering vs. normal disfluencies, and the informal usage of the word "stuttering" on the part of teachers and parents to describe typical disfluencies.

Stuttering Behavior in a National Age Cohort of Norwegian First-Graders With Down Syndrome

PURPOSE

The aims of this study were to investigate the occurrence of stuttering behavior across time and to evaluate the relationship between stuttering behavior and language ability in children with Down syndrome.

METHOD

A national age cohort of Norwegian first graders with Down syndrome (N = 75) participated in the study. Speech samples from a story-retelling task and a picture book dialogue as well as standardized measures of vocabulary, grammar, and nonverbal mental ability were collected at two time points approximately 5 months apart. Stuttering behavior was evaluated through counting stuttering-like disfluencies and stuttering severity ratings. The relationship between stuttering behavior and language ability was investigated through hierarchical regression analysis.

RESULTS

The participants had stuttering severity ratings ranging from no stuttering behavior to severe and displayed all types of stuttering-like disfluencies. There were significant relationships between stuttering behavior and language ability at the first time point, whereas the relationships were not significant at the second time point. The stuttering severity ratings were significantly predicted by language ability across time, whereas the frequency of stuttering-like disfluencies was not.

CONCLUSIONS

The occurrence of stuttering behavior was high across the measures and time points; however, the relationship between stuttering behavior and language ability varied across these variables. Thus, the nature of the relationship does not seem to follow a strict pattern that can be generalized to all children across time.

Novel word recognition in childhood stuttering

Language skills have long been posited to be a factor contributing to developmental stuttering. The current study aimed to evaluate whether novel word recognition, a critical skill for language development, differentiated children who stutter from children who do not stutter. Twenty children who stutter and 18 children who do not stutter, aged 3–8 years, completed a novel word recognition task. Real-time eye gaze was used to evaluate online learning. Retention was measured immediately and after a 1-hr delay. Children who stutter and children who do not stutter exhibited similar patterns of online novel word recognition. Both groups also had comparable retention accuracy. Together, these results revealed that novel word recognition and retention were similar in children who stutter and children who do not stutter. These patterns suggest that differences observed in previous studies of language in stuttering may not be driven by novel word recognition abilities in children who stutter.