Auditory‐motor adaptation is reduced in adults who stutter but not in children who stutter

Previous studies have shown that adults who stutter produce smaller corrective motor responses to compensate for unexpected auditory perturbations in comparison to adults who do not stutter, suggesting that stuttering may be associated with deficits in integration of auditory feedback for online speech monitoring. In this study, we examined whether stuttering is also associated with deficiencies in integrating and using discrepancies between expected and received auditory feedback to adaptively update motor programs for accurate speech production. Using a sensorimotor adaptation paradigm, we measured adaptive speech responses to auditory formant frequency perturbations in adults and children who stutter and their matched nonstuttering controls. We found that the magnitude of the speech adaptive response for children who stutter did not differ from that of fluent children. However, the adaptation magnitude of adults who stutter in response to auditory perturbation was significantly smaller than the adaptation magnitude of adults who do not stutter. Together these results indicate that stuttering is associated with deficits in integrating discrepancies between predicted and received auditory feedback to calibrate the speech production system in adults but not children. This auditory‐motor integration deficit thus appears to be a compensatory effect that develops over years of stuttering.     

The speech naturalness of people who stutter speaking under delayed auditory feedback as perceived by different groups of listeners

This study investigated listeners' perception of the speech naturalness of people who stutter (PWS) speaking under delayed auditory feedback (DAF) with particular attention for possible listener differences. Three panels of judges consisting of 14 stuttering individuals, 14 speech language pathologists, and 14 naive listeners rated the naturalness of speech samples of stuttering and non-stuttering individuals using a 9-point interval scale. Results clearly indicate that these three groups evaluate naturalness differently. Naive listeners appear to be more severe in their judgements than speech language pathologists and stuttering listeners, and speech language pathologists are apparently more severe than PWS. The three listener groups showed similar trends with respect to the relationship between speech naturalness and speech rate. Results of all three indicated that for PWS, the slower a speaker's rate was, the less natural speech was judged to sound. The three listener groups also showed similar trends with regard to naturalness of the stuttering versus the non-stuttering individuals. All three panels considered the speech of the non-stuttering participants more natural. EDUCATIONAL OBJECTIVES: The reader will be able to: (1) discuss the speech naturalness of people who stutter speaking under delayed auditory feedback, (2) discuss listener differences about the naturalness of people who stutter speaking under delayed auditory feedback, and (3) discuss the importance of speech rate for the naturalness of speech.     

A novel approach for measuring social participation in adults who stutter

This paper reports a preliminary study which trialled a novel approach for measuring speech output and social participation. The amount of phonation was accumulated via an objective measure called an Ambulatory Phonation Monitor (APM).Purpose(1) To establish whether adults who stutter will tolerate wearing an APM for an extended period of time (three days), (2) to test whether the APM can accumulate useful data about the amount of phonation adults who stutter produce in the course of a normal day and (3) to examine a possible relationship between stuttering severity and amount of phonation.MethodThree adults who stutter wore an APM for three consecutive days during their waking hours. Each completed a questionnaire regarding the device and kept a speech diary outlining daily speaking activities and self-reported stuttering severity. APM data regarding amount of phonation was collected, analysed and compared with the participants’ speech diaries.ResultsEach adult tolerated wearing the APM and while they felt comfortable speaking wearing the device, it was somewhat cumbersome. Variations in the amount of speaking across each day and in different speaking situations were evident. For two participants there was a positive correlation between phonation time and severity rating.ConclusionsPreliminary data suggests that the APM can provide valuable information about the amount adults who stutter speak. The APM is sufficiently sensitive to differentiate variations in the amount of phonation during different speaking situations. These favourable preliminary results suggest the value of a larger scale study.Educational Objectives: The reader will be able to: (a) describe the different aspects of stuttering currently routinely measured in clinical practice; (b) discuss the limitations of current measurement procedures; (c) discuss the advantages of speech measures obtained by an Ambulatory Phonation Monitor APM); (d) describe the perspectives of adults who stutter who have worn an APM to measure phonation time.     

Effect of reading with reversed speech on frequency of stuttering in adults

This study explored the effect of reading with reversed speech on the frequency of stuttering. Eight adults who stutter served as participants and read four 300-syllable passages while listening to three types of speech stimuli: normal speech (choral reading), reversed speech at normal speed, reversed speech at half speed, and a control condition of no auditory feedback. A repeated-measures analysis of variance showed a significant decrease in stuttering frequency in the choral reading condition but not in reversed speech at normal and half speed. However, the reversed speech at half-speed condition showed a large effect size (omega2 = 0.32). Data suggest that a forward moving speech feedback is not essential to decrease the frequency of stuttering in adults who stutter.     

The role of temporal speech cues in facilitating the fluency of adults who stutter

PurposeAdults who stutter speak more fluently during choral speech contexts than they do during solo speech contexts. The underlying mechanisms for this effect remain unclear, however. In this study, we examined the extent to which the choral speech effect depended on presentation of intact temporal speech cues. We also examined whether speakers who stutter followed choral signals more closely than typical speakers did.Method8 adults who stuttered and 8 adults who did not stutter read 60 sentences aloud during a solo speaking condition and three choral speaking conditions (240 total sentences), two of which featured either temporally altered or indeterminate word duration patterns. Effects of these manipulations on speech fluency, rate, and temporal entrainment with the choral speech signal were assessed.ResultsAdults who stutter spoke more fluently in all choral speaking conditions than they did when speaking solo. They also spoke slower and exhibited closer temporal entrainment with the choral signal during the mid- to late-stages of sentence production than the adults who did not stutter. Both groups entrained more closely with unaltered choral signals than they did with altered choral signals.ConclusionsFindings suggest that adults who stutter make greater use of speech-related information in choral signals when talking than adults with typical fluency do. The presence of fluency facilitation during temporally altered choral speech and conversation babble, however, suggests that temporal/gestural cueing alone cannot account for fluency facilitation in speakers who stutter. Other potential fluency enhancing mechanisms are discussed.Educational Objectives: The reader will be able to (a) summarize competing views on stuttering as a speech timing disorder, (b) describe the extent to which adults who stutter depend on an accurate rendering of temporal information in order to benefit from choral speech, and (c) discuss possible explanations for fluency facilitation in the presence of inaccurate or indeterminate temporal cues.     

Auditory backward-masking performance by children who stutter and its relation to dysfluency rate

The fluency of people who stutter is affected markedly when auditory feedback is altered, suggesting that stuttering may be associated with hearing. Peripheral hearing problems, however, are no more common in people who stutter than in those who do not. Performance was investigated in a task that involves central auditory processing (backward masking). Children who stuttered had deficits in backward masking (indicated by higher thresholds) compared with a group of fluent control children. The backward-masking thresholds were positively correlated with frequency of stuttering.     

The effect of fast speech rate on stuttering frequency during delayed auditory feedback

Delayed auditory feedback (DAF) has been documented to improve fluency in those who stutter. The increased fluency has been attributed to the slowed speech rate induced by DAF, but recent experiments have suggested that increasing the speech rate may also decrease stuttering under DAF. This investigation described the effect of combining a fast speech rate and DAF on the fluency of four people who stutter. Fluency of the two mildly dysfluent subjects was the same for both no DAF and DAF conditions at normal and at fast oral reading rates. In contrast, the two severely dysfluent subjects improved in fluency from the no DAF to the DAF conditions. They were found to be dysfluent at both normal and fast oral reading rates without DAF. The results of the study point to the need for further research on the relationship between speech rate and stuttering frequency under conditions of DAF and no DAF. EDUCATIONAL OBJECTIVES: Readers will learn about and be able to describe how the frequency of stuttering is affected by: (1) speech rates; (2) DAF; and (3) how stuttering severity influences such effects.     

Avoidance of eye gaze by adults who stutter

PurposeAdults who stutter are at significant risk of developing social phobia. Cognitive theorists argue that a critical factor maintaining social anxiety is avoidance of social information. This avoidance may impair access to positive feedback from social encounters that could disconfirm fears and negative beliefs. Adults who stutter are known to engage in avoidance behaviours, and may neglect positive social information. This study investigated the gaze behaviour of adults who stutter whilst giving a speech.Method16 adults who stutter and 16 matched controls delivered a 3-min speech to a television display of a pre-recorded lecture theatre audience. Participants were told the audience was watching them live from another room. Audience members were trained to display positive, negative and neutral expressions. Participant eye movement was recorded with an eye-tracker.ResultsThere was a significant difference between the stuttering and control participants for fixation duration and fixation count towards an audience display. In particular, the stuttering participants, compared to controls, looked for shorter time at positive audience members than at negative and neutral audience members and the background.ConclusionsAdults who stutter may neglect positive social cues within social situations that could serve to disconfirm negative beliefs and fears.Educational objectives: The reader will be able to: (a) describe the nature of anxiety experienced by adults who stutter; (b) identify the most common anxiety condition among adults who stutter; (c) understand how information processing biases and the use of safety behaviours contribute to the maintenance of social anxiety; (d) describe how avoiding social information may contribute to the maintenance of social anxiety in people who stutter; and (e) describe the clinical implications of avoidance of social information in people who stutter.     

The effect of SpeechEasy on stuttering frequency in laboratory conditions

The effect of SpeechEasy on stuttering frequency during speech produced in a laboratory setting was examined. Thirteen adults who stutter participated. Stuttering frequencies in two baseline conditions were compared to stuttering frequencies with the device fitted according to the manufacturer's protocol. The fitting protocol includes instructions for deliberate use of vowel prolongation. Relative to the initial baseline condition, stuttering was reduced by 74%, 36%, and 49% for reading, monologue, and conversation, respectively. In comparison, stuttering was reduced by 42%, 30%, and 36%, respectively with the device in place, but before participants were instructed to deliberately prolong vowels. Examination of individual response profiles revealed that although stuttering reduced in the device compared to the baseline conditions during at least one of three speech tasks for most participants, degree and pattern of benefit varied greatly across participants. EDUCATIONAL OBJECTIVES: The reader will be able to: (1) discuss recent research in altered auditory feedback that led to the development of SpeechEasy, (2) analyze and describe issues related to evaluating the treatment benefits of fluency aids, and (3) summarize the range of outcomes that were observed with SpeechEasy in this study.     

Factors affecting occupational advice for speakers who do and do not stutter

Factors affecting perceptions of occupational suitability were examined for speakers who stutter and speakers who do not stutter. In Experiment 1, 58 adults who do not stutter heard one of two audio recordings (less severe stuttering, more severe stuttering) of a speaker who stuttered. Participants rated the speaker's communicative functioning, personal attributes, and suitability for 32 occupations, along with perceptions of the occupations' speaking demands and educational requirements. Perceived speaking demand strongly affected occupational suitability ratings at both levels of stuttering severity. In Experiment 2, 58 additional adults who do not stutter heard a recording of another adult in one of two conditions (fluent speech, pseudo-stuttering), and provided the same ratings as in Experiment 1. In the pseudo-stuttering condition, participants' perceptions of occupational speaking demand again had a strong effect on occupational suitability ratings. In the fluent condition, suitability ratings were affected primarily by perceived educational demand; perceived speaking demand was of secondary importance. Across all participants in Experiment 2, occupational suitability ratings were associated with ratings of the speaker's personal attributes and communicative functioning. In both experiments, speakers who stuttered received lower suitability ratings for high speaking demand occupations than for low speaking demand occupations. Ratings for many high speaking occupations, however, fell just below the midpoint of the occupational suitability scale, suggesting that participants viewed these occupations as less appropriate, but not necessarily inappropriate, for people who stutter. Overall, the findings support the hypothesis that people who stutter may face occupational stereotyping and/or role entrapment in work settings. EDUCATIONAL OBJECTIVES: At the end of this activity the reader will be able to (a) summarize main findings on research related to the work-related experiences of people who stutter, (b) describe factors that affect perceptions of which occupations are best suited for speakers who stutter and speakers who do not stutter, and (c) discuss how findings from the present study relate to previous findings on occupational advice for people who stutter.     

Language and motor abilities of preschool children who stutter: Evidence from behavioral and kinematic indices of nonword repetition performance

Stuttering is a disorder of speech production that typically arises in the preschool years, and many accounts of its onset and development implicate language and motor processes as critical underlying factors. There have, however, been very few studies of speech motor control processes in preschool children who stutter. Hearing novel nonwords and reproducing them engages multiple neural networks, including those involved in phonological analysis and storage and speech motor programming and execution. We used this task to explore speech motor and language abilities of 31 children aged 4–5 years who were diagnosed as stuttering. We also used sensitive and specific standardized tests of speech and language abilities to determine which of the children who stutter had concomitant language and/or phonological disorders. Approximately half of our sample of stuttering children had language and/or phonological disorders. As previous investigations would suggest, the stuttering children with concomitant language or speech sound disorders produced significantly more errors on the nonword repetition task compared to typically developing children. In contrast, the children who were diagnosed as stuttering, but who had normal speech sound and language abilities, performed the nonword repetition task with equal accuracy compared to their normally fluent peers. Analyses of interarticulator motions during accurate and fluent productions of the nonwords revealed that the children who stutter (without concomitant disorders) showed higher variability in oral motor coordination indices. These results provide new evidence that preschool children diagnosed as stuttering lag their typically developing peers in maturation of speech motor control processes.Educational objectives: The reader will be able to: (a) discuss why performance on nonword repetition tasks has been investigated in children who stutter; (b) discuss why children who stutter in the current study had a higher incidence of concomitant language deficits compared to several other studies; (c) describe how performance differed on a nonword repetition test between children who stutter who do and do not have concomitant speech or language deficits; (d) make a general statement about speech motor control for nonword production in children who stutter compared to controls.     

Functional brain activation differences in stuttering identified with a rapid fMRI sequence

The purpose of this study was to investigate whether brain activity related to the presence of stuttering can be identified with rapid functional MRI (fMRI) sequences that involved overt and covert speech processing tasks. The long-term goal is to develop sensitive fMRI approaches with developmentally appropriate tasks to identify deviant speech motor and auditory brain activity in children who stutter closer to the age at which recovery from stuttering is documented. Rapid sequences may be preferred for individuals or populations who do not tolerate long scanning sessions. In this report, we document the application of a picture naming and phoneme monitoring task in 3 min fMRI sequences with adults who stutter (AWS). If relevant brain differences are found in AWS with these approaches that conform to previous reports, then these approaches can be extended to younger populations. Pairwise contrasts of brain BOLD activity between AWS and normally fluent adults indicated the AWS showed higher BOLD activity in the right inferior frontal gyrus (IFG), right temporal lobe and sensorimotor cortices during picture naming and higher activity in the right IFG during phoneme monitoring. The right lateralized pattern of BOLD activity together with higher activity in sensorimotor cortices is consistent with previous reports, which indicates rapid fMRI sequences can be considered for investigating stuttering in younger participants.Educational objectives: The reader will learn about and be able to describe the: (1) use of functional MRI to study persistent developmental stuttering; (2) differences in brain activation between persons who stutter and normally fluent speakers; and (3) potential benefit of time efficient fMRI sequences combined with a range of speech processing tasks for investigating stuttering in younger populations.     

Atypical central auditory speech-sound discrimination in children who stutter as indexed by the mismatch negativity

PurposeRecent theoretical conceptualizations suggest that disfluencies in stuttering may arise from several factors, one of them being atypical auditory processing. The main purpose of the present study was to investigate whether speech sound encoding and central auditory discrimination, are affected in children who stutter (CWS).MethodsParticipants were 10 CWS, and 12 typically developing children with fluent speech (TDC). Event-related potentials (ERPs) for syllables and syllable changes [consonant, vowel, vowel-duration, frequency (F0), and intensity changes], critical in speech perception and language development of CWS were compared to those of TDC.ResultsThere were no significant group differences in the amplitudes or latencies of the P1 or N2 responses elicited by the standard stimuli. However, the Mismatch Negativity (MMN) amplitude was significantly smaller in CWS than in TDC. For TDC all deviants of the linguistic multifeature paradigm elicited significant MMN amplitudes, comparable with the results found earlier with the same paradigm in 6-year-old children. In contrast, only the duration change elicited a significant MMN in CWS.ConclusionsThe results showed that central auditory speech-sound processing was typical at the level of sound encoding in CWS. In contrast, central speech-sound discrimination, as indexed by the MMN for multiple sound features (both phonetic and prosodic), was atypical in the group of CWS. Findings were linked to existing conceptualizations on stuttering etiology.Educational objectives: The reader will be able (a) to describe recent findings on central auditory speech-sound processing in individuals who stutter, (b) to describe the measurement of auditory reception and central auditory speech-sound discrimination, (c) to describe the findings of central auditory speech-sound discrimination, as indexed by the mismatch negativity (MMN), in children who stutter.     

Multilingual children who stutter: clinical issues

Stuttering occurs across all languages and cultures. However, the impact of speaking more than one language on assessment and treatment of young children who stutter is not well documented. This paper discusses some of the challenges related to clinical issues pertaining to this population including (a) identifying stuttering in an unfamiliar language, (b) the influence of language proficiency, and (c) treatment of multilingual young children who stutter. The paper is written from the perspective of the author's experience treating multilingual children who stutter within the context of the linguistic and cultural diversity of Canada, notably in the French speaking Province of Quebec where many children grow up speaking two or more languages in everyday life. Clinical examples will be taken from the evidence-based literature as well as the author's clinical experience.Educational objectives: After reading this paper, the learner will be able to (1) summarize the literature regarding assessment and treatment of stuttering in young children speaking more than one language, (2) summarize some of the challenges related to this issue and (3) describe some of the findings associated with treatment of bilingual children who stutter and (4) be prepared to apply some of these suggestions in the treatment of bilingual children who stutter.     

Stuttering, emotions, and heart rate during anticipatory anxiety: a critical review

Persons who stutter often report their stuttering is influenced by emotional reactions, yet the nature of such relation is still unclear. Psychophysiological studies of stuttering have failed to find any major association between stuttering and the activity of the sympathetic nervous system. A review of published studies of heart rate in relation to stressful speech situations indicate that adults who stutter tend to show a paradoxical reduction of heart rate compared with nonstuttering persons. Reduction of heart rate has also been observed in humans and mammals during anticipation of an unpleasant stimulus, and is proposed to be an indication of anticipatory anxiety resulting in a "freezing response" with parasympathetic inhibition of the heart rate. It is suggested that speech-related anticipatory anxiety in persons who stutter is likely to be a secondary, conditioned reaction based on previous experiences of stuttering. EDUCATIONAL OBJECTIVES: The reader will be able to: (1) describe how the autonomic nervous system is modulated by emotional responses; (2) explain how anticipatory fear often results in inhibition of heart rate due to parasympathetic activation; (3) discuss why emotional reactions in persons who stutter may be secondary to negative experiences of speech problems.     

Speech disruption under delayed auditory feedback in multilingual speakers

The present study investigated the language familiarity hypothesis formulated by Mackay [(1970). How does language familiarity influence stuttering under delayed auditory feedback? Perceptual and Motor Skills, 30, 655-669] that bilinguals speak faster and stutter less under delayed auditory feedback (DAF) when speaking their more familiar language than a less familiar language. Thirty normally fluent native speakers of Dutch (17 males and 13 females, aged between 18;1 and 26;4 years) who were also proficient in French and English read meaningful and nonsense text under DAF in their mother tongue and in the two later acquired languages. The existence of a language familiarity effect was confirmed. The participants required significantly more time and showed significantly more speech disruptions under DAF in the later acquired languages than in the mother tongue, and reading time and number of speech disruptions was significantly higher for the nonsense texts than for the meaningful text for each of the three languages. An additional question addressed was whether or not there were any gender differences in the susceptibility to DAF. Results did not reveal a clear gender difference. EDUCATIONAL OBJECTIVES: The reader will be able to: (1) summarize the importance of language familiarity for the degree of speech disruption experienced by normally fluent multilingual speakers under delayed auditory feedback; and (2) describe gender differences in the susceptibility to delayed auditory feedback.     

Converting between word and syllable counts in children's conversational speech samples

Several authors have suggested that it is possible to convert between word and syllable counts for basic clinical measurements such as the frequency of speech disfluencies or speaking rate in conversational speech samples. Based primarily on results from adults' speech samples, proposed conversion factors have averaged approximately 1.5 syllables per word. Because children produce fewer multisyllabic words than adults, this conversion factor is probably not appropriate for children's speech samples. This study sought to develop a more accurate conversion factor for children's speech by comparing syllable and word counts in spontaneous speech samples produced by 50 children, age 3 to 5. Analyses revealed an average ratio of 1.15 syllables per word, which was consistent across different subjects, across subject groups (children who stutter and children who do not stutter) and also, somewhat surprisingly, across age groups (3-year olds, 4-year olds, and 5-year olds). Results suggest that this constant conversion factor of 1.15 can be used to convert between word and syllable with sufficient precision to allow clinicians to compare their data to published guidelines and benchmarks about childhood stuttering.     

Responses of adults who stutter to the anticipation of stuttering

PurposeMany people who stutter experience the phenomenon of anticipation—the sense that stuttering will occur before it is physically and overtly realized. A systematic investigation of how people who stutter respond to anticipation has not been previously reported. The purposes of this study were to provide self-report evidence of what people do in response to anticipation of stuttering and to determine the extent to which this anticipation occurs.MethodsThirty adults who stutter indicated on a Likert rating scale the extent to which they anticipate stuttering and answered three open-ended (written) questions regarding how they respond to anticipation.ResultsAll participants reported experiencing anticipation at least “sometimes,” and 77% of the participants reported experiencing anticipation “often” or “always.” The extent to which participants reported experiencing anticipation was not related to stuttering severity, impact, or treatment history. Analysis of written responses revealed 24 major categories, which were heuristically divided into action or non-action responses. Categories representing avoidance and self-management strategies were further divided into 14 and 19 subcategories, respectively. Participants were just as likely to view anticipation as helpful as they were to view it as harmful.ConclusionFindings demonstrate that most, if not all, adults who stutter experience anticipation, and the majority of adults who stutter report doing so at least often. Adults who stutter respond to this anticipation by altering the speech production process in various ways. Results highlight the importance of the role that anticipation plays in how stuttering behaviors manifest themselves.Educational Objectives: The reader will be able to: (a) summarize existing literature on the anticipation of stuttering; (b) describe the role and extent of anticipation of stuttering in adults; (c) describe the various ways that adults who stutter respond to anticipation; (d) describe the importance of measuring anticipation in clinical and research domains.     

Stuttering and sensory gating: a study of acoustic startle prepulse inhibition

It was hypothesized that stuttering may be related to impaired sensory gating, leading to overflow of superfluous disturbing auditory feedback and breakdown of the speech sequence. This hypothesis was tested using the acoustic startle prepulse inhibition (PPI) paradigm. A group of 22 adults with developmental stuttering were compared with controls regarding the degree of PPI. No significant differences were found between the stuttering adults and the control group; the groups showed similar means and distribution. Likewise, no relation between the degree of PPI and the effect of altered auditory feedback on stuttering was found. In summary, the results of the study indicate that there is no relation between stuttering and PPI.