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Background: Evidence-based practice involves the synthesis of multiple forms of evidence to inform clinical decision-making and treatment evaluation. Practice- and patient-based evidence are two forms of evidence that are under-represented in the stuttering literature. The collection of such knowledge is essential to support the design and delivery of effective stuttering interventions for adults. Aims: To build stakeholder consensus on the core components of intervention for adults who stutter, and to establish a guiding framework for the design and development of evidence-based interventions for adults who stutter. Methods & Procedures: Adults who stutter and speech and language therapists (SLTs) with experience in providing stuttering intervention participated in the three-round e-Delphi Survey focused on--(1) identifying key stuttering intervention components, including principles, practices, and structural and contextual elements; and (2) obtaining group consensus on stuttering intervention components. Statements were categorized using the International Classification of Functioning, Disability and Health (ICF) model adapted to the study of stuttering. Outcomes & Results: A total of 48 individuals agreed to participate--48/48 (100%) completed the Round 1 questionnaire, 40/48 (83%) responded to Round 2 and 36/40 (90%) participated in Round 3. Following content analysis of Round 1, 101 statements were developed, and consensus was achieved on 89 statements perceived as representing the core components of stuttering intervention for adults. Categorization of these statements reflected the key stuttering intervention components relating to personal reactions to stuttering, limitations in life participation and environmental factors. Conclusions & Implications: Consensus on the core components of stuttering intervention was reached through engagement with key stakeholders. The evidence-based framework presented highlights the range of key intervention components a clinician should consider when designing interventions for adults who stutter.

Purpose: The purpose of this study was to test whether adults who stutter (AWS) display a different range of sensitivity to delayed auditory feedback (DAF). Two experiments were conducted to assess the fluency of AWS under long-latency DAF and to test the effect of short-latency DAF on speech kinematic variability in AWS. Method: In Experiment 1, 15 AWS performed a conversational speaking task under nonaltered auditory feedback and 250-ms DAF. The rates of stuttering-like disfluencies, other disfluencies, and speech errors and articulation rate were compared. In Experiment 2, 13 AWS and 15 adults who do not stutter (AWNS) read three utterances under four auditory feedback conditions: nonaltered auditory feedback, amplified auditory feedback, 25-ms DAF, and 50-ms DAF. Across-utterance kinematic variability (spatiotemporal index) and within-utterance variability (percent determinism and stability) were compared between groups. Results: In Experiment 1, under 250-ms DAF, the rate of stuttering-like disfluencies and speech errors increased significantly, while articulation rate decreased significantly in AWS. In Experiment 2, AWS exhibited higher kinematic variability than AWNS across the feedback conditions. Under 25-ms DAF, the spatiotemporal index of AWS decreased significantly compared to the other feedback conditions. AWS showed lower overall percent determinism than AWNS, but their percent determinism increased under 50-ms DAF to approximate that of AWNS. Conclusions: Auditory feedback manipulations can alter speech fluency and kinematic variability in AWS. Longer latency auditory feedback delays induce speech disruptions, while subtle auditory feedback manipulations potentially benefit speech motor control. Both AWS and AWNS are susceptible to auditory feedback during speech production, but AWS appear to exhibit a distinct continuum of sensitivity.

Purpose: Our knowledge of speech rate development remains inadequate because of limited longitudinal data and lack of data from children under age 3;0 (years;months). The purpose of this longitudinal study was to test the pattern of speech rate development between ages 2;0 and 3;0. Method: Speech rate was assessed at 4 time points between ages 2;0 and 3;0. The analysis employed multilevel models to characterize the development of speech rate (syllables per second), phonemes per second (PPS), length of active declarative sentences, and mean length of utterance. Results: The results indicate a significant linear increase in speech rate, PPS, length of active declarative sentences, and mean length of utterance occurring over the 1-year period. Male and female children differed in speech rate, PPS, and utterance length, suggesting sex is a potential factor in early speech rate development. Conclusions: Our findings indicate that the speech motor system develops rapidly during the period when grammar emerges. Speech rate has the potential to be an important metric for understanding typical speech development and speech disorders.

Purpose: The purpose of this study was to test whether adults who stutter (AWS) display a different range of sensitivity to delayed auditory feedback (DAF). Two experiments were conducted to assess the fluency of AWS under long-latency DAF and to test the effect of short-latency DAF on speech kinematic variability in AWS. Method: In Experiment 1,15 AWS performed a conversational speaking task under nonaltered auditory feedback and 250-ms DAF. The rates of stuttering-like disfluencies, other disfluencies, and speech errors and articulation rate were compared. In Experiment 2, 13 AWS and 15 adults who do not stutter (AWNS) read three utterances under four auditory feedback conditions: nonaltered auditory feedback, amplified auditory feedback, 25-ms DAF, and 50-ms DAF. Across-utterance kinematic variability (spatiotemporal index) and within-utterance variability (percent determinism and stability) were compared between groups. Results: In Experiment 1, under 250-ms DAF, the rate of stuttering-like disfluencies and speech errors increased significantly, while articulation rate decreased significantly in AWS. In Experiment 2, AWS exhibited higher kinematic variability than AWNS across the feedback conditions. Under 25-ms DAF, the spatiotemporal index of AWS decreased significantly compared to the other feedback conditions. AWS showed lower overall percent determinism than AWNS, but their percent determinism increased under 50-ms DAF to approximate that of AWNS. Conclusions: Auditory feedback manipulations can alter speech fluency and kinematic variability in AWS. Longer latency auditory feedback delays induce speech disruptions, while subtle auditory feedback manipulations potentially benefit speech motor control. Both AWS and AWNS are susceptible to auditory feedback during speech production, but AWS appear to exhibit a distinct continuum of sensitivity., The relationship between sensorimotor integration and speech production is a central issue in the search for the cause of stuttering and for delivering innovative intervention. There has been a consensus [...]

Purpose: Our knowledge of speech rate development remains inadequate because of limited longitudinal data and lack of data from children under age 3;0 (years; months). The purpose of this longitudinal study was to test the pattern of speech rate development between ages 2;0 and 3;0. Method: Speech rate was assessed at 4 time points between ages 2;0 and 3;0. The analysis employed multilevel models to characterize the development of speech rate (syllables per second), phonemes per second (PPS), length of active declarative sentences, and mean length of utterance. Results: The results indicate a significant linear increase in speech rate, PPS, length of active declarative sentences, and mean length of utterance occurring over the 1-year period. Male and female children differed in speech rate, PPS, and utterance length, suggesting sex is a potential factor in early speech rate development. Conclusions: Our findings indicate that the speech motor system develops rapidly during the period when grammar emerges. Speech rate has the potential to be an important metric for understanding typical speech development and speech disorders., The rate of speech is a product of several factors including sensorimotor and language processes (e.g., Allen, 1973; Kent, 1976, 2004; Nip & Green, 2013; Redford, 2015). As these factors [...]

A study was conducted to examine production variability in American Sign Language (ASL) in order to gain insight into the development of motor control in a language produced in another modality. Production variability was characterized through the spatiotemporal index (STI), which represents production stability in whole utterances and is a function of variability in effector displacement waveforms (Smith et al., 1995). Motion capture apparatus was used to acquire wrist displacement data across a set of eight target signs embedded in carrier phrases. The STI values of Deaf signers and hearing learners at three different ASL experience levels were compared to determine whether production stability varied as a function of time spent acquiring ASL. We hypothesized that lower production stability as indexed by the STI would be evident for beginning ASL learners, indicating greater production variability, with variability decreasing as ASL language experience increased. As predicted, Deaf signers showed significantly lower STI values than the hearing learners, suggesting that stability of production is indeed characteristic of increased ASL use. The linear trend across experience levels of hearing learners was not statistically significant in all spatial dimensions, indicating that improvement in production stability across relatively short time scales was weak. This novel approach to characterizing production stability in ASL utterances has relevance for the identification of sign production disorders and for assessing L2 acquisition of sign languages.

A phenomenon called "repetition reduction" can increase articulation rate in adults by facilitating phonetic and motor processes, which indicates flexibility in the control of articulation rate. Young children, who speak much slower, may not have the same speech motor flexibility resulting in the absence of the repetition reduction effect. In this study, we tested whether spontaneous repetitions of young children are produced with a faster articulation rate than their original utterances. Twelve monolingual English-speaking children were observed at four time points between 2;0 and 3;0 years of age. A significant increase in articulation rate and syllable count was found using multilevel models for all utterances over the 1-year period. At each time point, however, the repeated utterances were produced significantly faster than the original utterances even though the content and syllable count differed minimally. Our findings conform to the pattern of adult studies suggesting that a "naturistic" form of repetition reduction is already present in the speech of children at 2;0 years. Although certain aspects of speech motor control are undergoing rapid development, existing motor capability at 2;0 already supports flexible changes in articulation rate including repetition reduction. [ABSTRACT FROM AUTHOR]

A deficiency in sensorimotor integration in a person who stutters may be a factor in the pathophysiology of developmental stuttering. To test oral sensorimotor function in adults who stutter, we used a task that requires the coordination of a jaw-opening movement with phonation onset. The task was adapted from previous limb coordination studies, which show that movement coordination depends on intact proprioception. We hypothesized that adult stutterers would show deficient jaw-phonatory coordination relative to control participants. The task required initiation of phonation as a jaw-opening movement passed through a narrow spatial target. Target amplitude and jaw movement speed were varied. The stuttering group showed significantly higher movement error and spatial variability in jaw-phonatory coordination compared to the control group, but group differences in movement velocity or duration were not found. The aberrant jaw-phonatory coordination of the stuttering participants suggests that stuttering is associated with an oral proprioceptive limitation, although, the findings are also consistent with a motor control deficit. Learning outcomes: As a result of this activity, reader will (1) learn about a hypothesis and evidence supporting the view that a sensorimotor deficit contributes to chronic developmental stuttering and (2) will obtain information about the role of proprioception in multi-articulatory coordination and how it can be tested using an oral-phonatory coordination task.

Background: Evidence‐based practice involves the synthesis of multiple forms of evidence to inform clinical decision‐making and treatment evaluation. Practice‐ and patient‐based evidence are two forms of evidence that are under‐represented in the stuttering literature. The collection of such knowledge is essential to support the design and delivery of effective stuttering interventions for adults. Aims: To build stakeholder consensus on the core components of intervention for adults who stutter, and to establish a guiding framework for the design and development of evidence‐based interventions for adults who stutter. Methods & Procedures: Adults who stutter and speech and language therapists (SLTs) with experience in providing stuttering intervention participated in the three‐round e‐Delphi Survey focused on: (1) identifying key stuttering intervention components, including principles, practices, and structural and contextual elements; and (2) obtaining group consensus on stuttering intervention components. Statements were categorized using the International Classification of Functioning, Disability and Health (ICF) model adapted to the study of stuttering. Outcomes & Results: A total of 48 individuals agreed to participate: 48/48 (100%) completed the Round 1 questionnaire, 40/48 (83%) responded to Round 2 and 36/40 (90%) participated in Round 3. Following content analysis of Round 1, 101 statements were developed, and consensus was achieved on 89 statements perceived as representing the core components of stuttering intervention for adults. Categorization of these statements reflected the key stuttering intervention components relating to personal reactions to stuttering, limitations in life participation and environmental factors. Conclusions & Implications: Consensus on the core components of stuttering intervention was reached through engagement with key stakeholders. The evidence‐based framework presented highlights the range of key intervention components a clinician should consider when designing interventions for adults who stutter. What this paper adds: What is already known on the subject: Evidence‐based practice endorses the synthesis of multiple knowledge forms including research, practice and patient evidence to support clinical decision‐making and treatment evaluation. The stuttering literature is characterized by an over‐representation of efficacy evidence, with significantly less practice and patient evidence to guide clinical practice. What this paper adds to existing knowledge: This study adds valuable practice‐ and patient‐based evidence for effective stuttering intervention components for adults who stutter. These relate to personal reactions to stuttering, limitations in life participation and environmental factors. What are the potential or actual clinical implications of this work?: This research presents a stakeholder‐informed framework for stuttering intervention to guide SLTs working with adults who stutter in designing evidence‐based interventions. The framework supports the adoption of a person‐centred approach to intervention to ensure each client's unique needs, preferences, values and desired outcomes are explored and integrated into therapy. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to test whether adults who stutter (AWS) display a different range of sensitivity to delayed auditory feedback (DAF). Two experiments were conducted to assess the fluency of AWS under long-latency DAF and to test the effect of short-latency DAF on speech kinematic variability in AWS. Method: In Experiment 1, 15 AWS performed a conversational speaking task under nonaltered auditory feedback and 250-ms DAF. The rates of stuttering-like disfluencies, other disfluencies, and speech errors and articulation rate were compared. In Experiment 2, 13 AWS and 15 adults who do not stutter (AWNS) read three utterances under four auditory feedback conditions: nonaltered auditory feedback, amplified auditory feedback, 25-ms DAF, and 50-ms DAF. Across-utterance kinematic variability (spatiotemporal index) and within-utterance variability (percent determinism and stability) were compared between groups. Results: In Experiment 1, under 250-ms DAF, the rate of stuttering-like disfluencies and speech errors increased significantly, while articulation rate decreased significantly in AWS. In Experiment 2, AWS exhibited higher kinematic variability than AWNS across the feedback conditions. Under 25-ms DAF, the spatiotemporal index of AWS decreased significantly compared to the other feedback conditions. AWS showed lower overall percent determinism than AWNS, but their percent determinism increased under 50-msDAFtoapproximatethatofAWNS. Conclusions: Auditory feedback manipulations can alter speech fluency and kinematic variability in AWS. Longer latency auditory feedback delays induce speech disruptions, while subtle auditory feedback manipulations potentially benefit speech motor control. Both AWS and AWNS are susceptible to auditory feedback during speech production, but AWS appear to exhibit a distinct continuum of sensitivity. [ABSTRACT FROM AUTHOR]

Audiomotor and visuomotor short-term memory are required for an important variety of skilled movements but have not been compared in a direct manner previously. Audiomotor memory capacity might be greater to accommodate auditory goals that are less directly related to movement outcome than for visually guided tasks. Subjects produced continuous isometric force with the right index finger under auditory and visual feedback. During the irst 10 s of each trial, subjects received continuous auditory or visual feedback. For the following 15 s, feedback was removed but the force had to be maintained accurately. An internal effort condition was included to test memory capacity in the same manner but without external feedback. Similar decay times of ~5-6 s were found for vision and audition but the decay time for internal effort was ~4 s. External feedback thus provides an advantage in maintaining a force level after feedback removal, but may not exclude some contribution from a sense of effort. Short-term memory capacity appears longer than certain previous reports but there may not be strong distinctions in capacity across different sensory modalities, at least for isometric force. [ABSTRACT FROM AUTHOR]

Repetition reduces word duration. Explanations of this process have appealed to audience design, internal production mechanisms, and combinations thereof [e.g. Kahn, J. M., & Arnold, J. E. (2015). Articulatory and lexical repetition effects on durational reduction: Speaker experience vs. common ground. Language, Cognition and Neuroscience, 30, 103–119]. Jacobs, Yiu, Watson, and Dell [2015. Why are repeated words produced with reduced durations? Evidence from inner speech and homophone production. Journal of Memory and Language, 84, 37–48] proposed the auditory feedback hypothesis, which states that speakers must hear a word, produced either by themselves or another speaker, in order for duration reduction on a subsequent production. We conducted a strong test of the auditory feedback hypothesis in two experiments, in which we used masked auditory feedback and whispering to prevent speakers from hearing themselves fully. Both experiments showed that despite limiting the sources of normal auditory feedback, repetition reduction was observed to equal extents in masked and unmasked conditions, suggesting that repetition reduction may be supported by multiple sources, such as somatosensory feedback and feedforward signals, depending on their availability. [ABSTRACT FROM AUTHOR]

Stuttering is a multifactorial disorder that is characterized by disruptions in the forward flow of speech believed to be caused by differences in the motor and linguistic systems. Several psycholinguistic theories of stuttering suggest that delayed or disrupted phonological encoding contributes to stuttered speech. However, phonological encoding remains difficult to measure without controlling for the involvement of the speech-motor system. Eye-tracking is proposed to be a reliable approach for measuring phonological encoding duration while controlling for the influence of speech production. Eighteen adults who stutter and 18 adults who do not stutter read nonwords under silent and overt conditions. Eye-tracking was used to measure dwell time, number of fixations, and response time. Adults who stutter demonstrated significantly more fixations and longer dwell times during overt reading than adults who do not stutter. In the silent condition, the adults who stutter produced more fixations on the nonwords than adults who do not stutter, but dwell-time differences were not found. Overt production may have resulted in additional requirements at the phonological and phonetic levels of encoding for adults who stutter. Direct measurement of eye-gaze fixation and dwell time suggests that adults who stutter require additional processing that could potentially delay or interfere with phonological-to-motor encoding. [ABSTRACT FROM AUTHOR]

The role of proprioception in speech and oral motor control was investigated by applying tendon vibration to the masseter during vowel production and nonspeech oral movements. Measures were made of peak jaw-opening amplitude, jaw-opening velocity, and movement time in both vibration and nonvibration conditions. Generally, the tendon vibration caused a consistent and marked reduction in the amplitude and velocity of jaw-opening movements for each subject in both tasks. Movement time remained consistent across the vibration conditions for both tasks. These results indicate that masseter tendon vibration causes significant changes in jaw kinematics during simple speech gestures and nonspeech movements. These findings are consistent with the documented effects of tendon vibration on limb movements. The study demonstrates that tendon vibration is a potent tool for investigating proprioception in speech and oral motor control. KEY WORDS: speech production, proprioception, tendon vibration, masseter, muscle spindles, Proprioception, which is the sensation of articulatory movement and position that arises from somatosensory receptors in muscle, skin, and joints (Prochazka, 1996), has a fundamental role in the coordination of [...]

In the typical speech of any language, voicing onset and offset are effortlessly coordinated with articulation as part of the intrinsic coordination of sound production. In this paper, we argue that voicing-articulatory coordination patterns could be shaped by sensory feedback during early speech learning and these patterns persist in mature syllable productions. Our experimental results show that voicing onset is closely associated with the peak velocity and peak amplitude of jaw and upper lip movements for VC syllables in adults. This robust coordination in the onset position may function to increase the salience of VC syllables and provide a phonetically natural explanation for vowels to undergo phonological lengthening and to avoid phonological reduction in word-initial onset position., (2010 S. Karger AG, Basel.)

The issue of whether speech is supported by the same neural substrates as non-speech vocal tract gestures has been contentious. In this fMRI study we tested whether producing non-speech vocal tract gestures in humans shares the same functional neuroanatomy as non-sense speech syllables. Production of non-speech vocal tract gestures, devoid of phonological content but similar to speech in that they had familiar acoustic and somatosensory targets, was compared to the production of speech syllables without meaning. Brain activation related to overt production was captured with BOLD fMRI using a sparse sampling design for both conditions. Speech and non-speech were compared using voxel-wise whole brain analyses, and ROI analyses focused on frontal and temporoparietal structures previously reported to support speech production. Results showed substantial activation overlap between speech and non-speech function in regions. Although non-speech gesture production showed greater extent and amplitude of activation in the regions examined, both speech and non-speech showed comparable left laterality in activation for both target perception and production. These findings posit a more general role of the previously proposed "auditory dorsal stream" in the left hemisphere--to support the production of vocal tract gestures that are not limited to speech processing.

Although stuttering is regarded as a speech-specific disorder, there is a growing body of evidence suggesting that subtle abnormalities in the motor planning and execution of non-speech gestures exist in stuttering individuals. We hypothesized that people who stutter (PWS) would differ from fluent controls in their neural responses during motor planning and execution of both speech and non-speech gestures that had auditory targets. Using fMRI with sparse sampling, separate BOLD responses were measured for perception, planning, and fluent production of speech and non-speech vocal tract gestures. During both speech and non-speech perception and planning, PWS had less activation in the frontal and temporoparietal regions relative to controls. During speech and non-speech production, PWS had less activation than the controls in the left superior temporal gyrus (STG) and the left pre-motor areas (BA 6) but greater activation in the right STG, bilateral Heschl's gyrus (HG), insula, putamen, and precentral motor regions (BA 4). Differences in brain activation patterns between PWS and controls were greatest in females and less apparent in males. In conclusion, similar differences in PWS from the controls were found during speech and non-speech; during perception and planning they had reduced activation while during production they had increased activity in the auditory area on the right and decreased activation in the left sensorimotor regions. These results demonstrated that neural activation differences in PWS are not speech-specific.

Cough and sniff are both spontaneous respiratory behaviors that can be initiated voluntarily in humans. Disturbances of cough may be life threatening, while inability to sniff impairs the sense of smell in neurological patients. Cortical mechanisms of voluntary cough and sniff production have been predicted to exist; however, the localization and function of supramedullary areas responsible for these behaviors are poorly understood. We used functional magnetic resonance imaging to identify the central control of voluntary cough and sniff compared with breathing. We determined that both voluntary cough and sniff require a widespread pattern of sensorimotor activation along the Sylvian fissure convergent with voluntary breathing. Task-specific activation occurred in a pontomesencephalic region during voluntary coughing and in the hippocampus and piriform cortex during voluntary sniffing. Identification of the localization of cortical activation for cough control in humans may help potential drug development to target these regions in patients with chronic cough. Understanding the sensorimotor sniff control mechanisms may provide a new view on the cerebral functional reorganization of olfactory control in patients with neurological disorders.