Time estimation by adults who stutter.

In view of the fact that stuttering involves time pressure in communicative contexts, the aim of this investigation was to study the effect of stuttering on time estimation. Two matching groups of 47 adults each, one consisting of stutterers and the other of fluent speakers, estimated the duration of four verbal tasks-two that involved speaking and two that did not. Two methods of time estimation were used: production and reproduction. In production, participants were required to perform a task, terminating it when they felt that the specified interval had elapsed. In reproduction, participants were asked to estimate the duration of a task immediately after being stopped by the experimenter. The results reveal that the differences in time estimation between adults who stutter and fluent speakers were task dependent, with the stutterers estimating time less accurately on oral verbal tasks. The conversation task in particular highlighted the inaccuracy of their time estimation. Furthermore, severe stutterers estimated time less accurately than mild stutterers. The greatest inaccuracy was displayed by severe stutterers when estimating the time of an oral task by the production method. The results are discussed in terms of cognitive models based on attention to time, method measurement, and mental workload. Clinical implications are also suggested.     

Women who stutter: personality and speech characteristics

This investigation was undertaken to determine whether adult female stutterers, when compared to adult male stutterers, would (1) present a different pattern of speech fluency or (2) evidence reduced self-esteem or both. Spontaneous speech samples were obtained from 10 adult female stutterers, 10 adult male stutterers, and 10 adult female nonstutterers. All were administered the California Test of Personality and semantic differential forms designed to assess self-concept. The female stutterers produced significantly fewer instances of revision-incomplete phrase than either of the other two groups and were more heterogeneous with respect to total frequency of disfluency. The female stutterers evidenced a significantly higher level of self-esteem than the male stutterers. Moreover, unlike the male stutterers, the female stutterers did not consider themselves handicapped. This investigation indicates that there may be significant differences in the stuttering symptomatology of adults that are related to gender.     

Coordination of oral and laryngeal movements in the perceptually fluent speech of adults who stutter.

This work investigated whether stuttering and nonstuttering adults differ in the coordination of oral and laryngeal movements during the production of perceptually fluent speech. This question was addressed by completing correlation analyses that extended previous acoustic studies by others as well as inferential analyses based on the within-subject central tendency and variability of acoustic and physiological indices of oral-laryngeal control and coordination. Stuttering and nonstuttering adults produced the target /p/ as the medial consonant in C(1)V(1)#C(2)V(2)C(3) sequences (C = consonant; V = vowel or diphthong; # = word boundary) embedded in utterances differing in length and location of the target movements. No between-groups differences were found for across- or within-subject correlations between acoustic measures of stop gap and voice onset time (VOT). However, the acoustic data did show longer durations for devoicing interval and VOT in the stuttering versus nonstuttering individuals, in the absence of a difference for a proportional measure specifically reflecting oral-laryngeal relative timing. Analyses of combined kinematic and electroglottographic data revealed that the stuttering individuals' speech was also characterized by (a) longer durations from bilabial closing movement onset and peak velocity to V(1) vocal fold vibration offset and (b) greater within-subject variability for dependent variables that were physiological indices of devoicing interval and VOT, but again no between-groups differences were found for specific indices of oral-laryngeal relative timing. Overall, findings suggest that, for the production of voiceless bilabial stops in perceptually fluent speech, stuttering and nonstuttering adults differ in the duration of intervals defined by events within as well as across the oral and laryngeal subsystems, but the groups show similar patterns of relative timing for the involved oral and laryngeal movements.     

Quality of life in adults who stutter

Although persistent developmental stuttering is known to affect daily living, just how great the impact is remains unclear. Furthermore, little is known about the underlying mechanisms which lead to a diminished quality of life (QoL). The primary objective of this study is to explore to what extent QoL is impaired in adults who stutter (AWS). In addition, this study aims to identify determinants of QoL in AWS by testing relationships between stuttering severity, coping, functioning and QoL and by testing for differences in variable scores between two AWS subgroups: receiving therapy versus not receiving therapy. A total of 91 AWS filled in several questionnaires to assess their stuttering severity, daily functioning, coping style and QoL. The QoL instruments used were the Health Utility Index 3 (HUI3) and the EuroQoL EQ-5D and EQ-VAS. The results indicated that moderate to severe stuttering has a negative impact on overall quality of life; HUI3 derived QoL values varied from .91 (for mild stuttering) to .73 (for severe stuttering). The domains of functioning that were predominantly affected were the individual's speech, emotion, cognition and pain as measured by the HUI3 and daily activities and anxiety/depression as measured by the EQ-5D. AWS in the therapy group rated their stuttering as more severe and recorded more problems on the HUI3 speech domain than AWS in the non-therapy group. The EQ-VAS was the only instrument that showed a significant difference in overall QoL between groups. Finally, it was found that the relationship between stuttering severity and QoL was influenced by the individual's coping style (emotion-oriented and task-oriented). These findings highlight the need for further research into stuttering in relation to QoL, and for a broader perspective on the diagnosis and treatment of stuttering, which would take into consideration quality of life and its determinants.     

Influences of length and syntactic complexity on the speech motor stability of the fluent speech of adults who stutter.

The purpose of the present study was to investigate the impact of utterance length and syntactic complexity on the speech motor stability of adults who stutter. Lower lip movement was recorded from 8 adults who stutter and 8 normally fluent controls. They produced a target phrase in isolation (baseline condition) and the same phrase embedded in utterances of increased length and/or increased syntactic complexity. The spatiotemporal index (STI) was used to quantify the stability of lower lip movements across multiple repetitions of the target phrase. Results indicated: (a) Adults who stutter demonstrated higher overall STI values than normally fluent adults across all experimental conditions, indicating decreased speech motor stability; (b) the speech motor stability of normally fluent adults was not affected by increasing syntactic complexity, but the speech motor stability of adults who stutter decreased when the stimuli were more complex; (c) increasing the length of the target utterance (without increasing syntactic complexity) did not affect the speech motor stability of either speaker group. These results indicate that language formulation processes may affect speech production processes and that the speech motor systems of adults who stutter may be especially susceptible to the linguistic demands required to produce a more complex utterance. The present findings, therefore, support the hypothesis that linguistic complexity is one factor that contributes to the disruptions of speech motor stability characteristic of stuttering.     

Orofacial movements associated with fluent speech in persons who stutter.

This study was intended to replicate and extend previous findings that (a) during fluent speech persons who stutter (PS) and those who do not (NS) differ in their vocal tract closing movements (L. Max, A. J. Caruso, and V. L. Gracco, 2003) and (b) ratios relating lip and tongue speed to jaw speed increase with stuttering severity (M. D. McClean and C. R. Runyan, 2000). An electromagnetic system was used to record movements of the upper lip, lower lip, tongue, and jaw of 43 NS and 37 PS during productions of a nonsense phrase and a sentence. Measurement and analysis of movement speeds, durations, and ratios of lip and tongue speed to jaw speed were performed on fluent productions of a nonsense phrase and sentence. Statistical comparisons were made between PS with low and high stuttering severity levels (LPS and HPS) and NS. Significant variations across groups in movement speed and duration were observed, but the pattern of these effects was complex and did not replicate the results of the two earlier studies. In the nonsense phrase, significant reductions in lower lip closing duration, jaw closing duration, and jaw closing speed were seen in PS. In the sentence task, HPS showed elevated tongue opening and closing durations. For tongue opening in the sentence, LPS showed elevated speeds and HPS showed reduced speeds. The elevated speeds for LPS are interpreted as a contributing factor to speech disfluency, whereas the reduced speeds and increased durations in HPS are attributed to adaptive behavior intended to facilitate fluent speech. Significant group effects were not seen for the speed ratio measures. Results are discussed in relation to multivariate analyses intended to identify subgroups of PS.     

Phonation interval modification and speech performance quality during fluency-inducing conditions by adults who stutter

PurposeTo relate changes in four variables previously defined as characteristic of normally fluent speech to changes in phonatory behavior during oral reading by persons who stutter (PWS) and normally fluent controls under multiple fluency-inducing (FI) conditions.MethodTwelve PWS and 12 controls each completed 4 ABA experiments. During A phases, participants read normally. B phases were 4 different FI conditions: auditory masking, chorus reading, whispering, and rhythmic stimulation. Dependent variables were the durations of accelerometer-recorded phonated intervals; self-judged speech effort; and observer-judged stuttering frequency, speech rate, and speech naturalness. The method enabled a systematic replication of Ingham et al. (2009).ResultsAll FI conditions resulted in decreased stuttering and decreases in the number of short phonated intervals, as compared with baseline conditions, but the only FI condition that satisfied all four characteristics of normally fluent speech was chorus reading. Increases in longer phonated intervals were associated with decreased stuttering but also with poorer naturalness and/or increased speech effort. Previous findings concerning the effects of FI conditions on speech naturalness and effort were replicated.ConclusionsMeasuring all relevant characteristics of normally fluent speech, in the context of treatments that aim to reduce the occurrence of short-duration PIs, may aid the search for an explanation of the nature of stuttering and may also maximize treatment outcomes for adults who stutter.Learning outcomes: The reader will be able to (1) understand the differential effects of four well established fluency-inducing conditions on the quality of fluency of adult PWS and controls, (2) learn how intervals of phonation are modified during these conditions and (3) how the duration of specific intervals of phonation may be identified for their potential application in stuttering treatment.     

The distribution of phonated intervals in the speech of individuals who stutter.

PURPOSE: Previous research has demonstrated the fluency-improving effect of reducing the occurrence of short-duration, phonated intervals (PIs; approximately 30-150 ms) in individuals who stutter, prompting the hypothesis that PIs in these individuals' speech are not distributed normally, particularly in the short PI ranges. It has also been hypothesized that this nonnormal PI distribution will be present during the stutter-free speech of affected persons. METHOD: A comparison was made between the distributions of PIs during oral reading by adolescent and adult speakers who stuttered (n=13; 11 males) and by age- and gender-matched, normally fluent control participants. RESULTS: The results did not support these hypotheses. The results showed that although there were significantly fewer PIs in the speech of the speakers who stuttered (probably because of their slower speaking rate), there was no significant difference between the PI distributions of both speaker groups. This was also true for comparisons between the stutter-free speech of the affected speakers and matched periods of speech produced by the control participants. The PI distributions from both groups were highly correlated. CONCLUSION: The null hypothesis findings are discussed in relation to speech-motor- and neurologic-systems explanations for the fluency-inducing effects of reducing short PIs in the speech of individuals who stutter.     

The Five Factor Model of personality applied to adults who stutter

Previous research has not explored the Five Factor Model of personality among adults who stutter. Therefore, the present study investigated the five personality domains of Neuroticism, Extraversion, Openness, Agreeableness and Conscientiousness, as measured by the NEO Five Factor Inventory (NEO-FFI), in a sample of 93 adults seeking speech treatment for stuttering, and compared these scores with normative data from an Australian and a United States sample. Results revealed that NEO-FFI scores for the stuttering group were within the ‘average’ range for all five personality domains. However, adults who stutter were characterized by significantly higher Neuroticism, and significantly lower Agreeableness and Conscientiousness, than normative samples. No significant differences were found between groups on the dimensions of Extraversion and Openness. These results are discussed with reference to the relationship between personality factors among adults who stutter, their directionality, and implications for predicting treatment outcome.Learning outcomes: The reader will be able to: (1) describe the Five Factor Model of personality, including the NEO-FFI personality domains of Extraversion, Neuroticism, Openness, Agreeableness, and Conscientiousness, and (2) discuss differences in NEO-FFI domain scores between adults who stutter and normative samples, and (3) understand the clinical implications of personality profiles in terms of treatment process and outcome for adults who stutter.     

Individual and consensus judgments of disfluency types in the speech of persons who stutter.

Previous research has suggested that the reliability with which judges identify individual disfluency types, such as repetitions or prolongations of speech sounds, may be very poor. The use of disfluency types judgments in research and clinical applications is also complicated by important differences among the several disfluency-based characterizations of stuttered speech. In an attempt to address these problems, this study arranged for 30 judges to identify all disfluency types that they perceived to be present in 5-s audiovisually recorded speech stimuli, each in an Individual task and then with a partner in a Consensus task. Intrapair agreement and interpair agreement for occurrences of disfluency types (from Consensus conditions) were significantly higher than intrajudge and interjudge agreement for occurrences (from Individual conditions). Despite being higher than individual values, however, intrapair and interpair agreement for occurrences both averaged less than 50%. Results also showed that disfluency types judgments, interpreted in terms of three common disfluency-based definitions of stuttering, were not strongly related to previous assessments of whether these speech tokens contained or did not contain stuttering. When combined with previously available data, the present findings suggest caution in the use of disfluency types to describe or define stuttered speech.     

Stuttering frequency on content and function words in adults who stutter: a concept revisited.

This study investigated stuttering frequency as a function of grammatical word type (i.e., content and function). Ten adults who stutter participated. Participants recited aloud a list of 126 words consisting of an equal number of content and function words, which were presented individually and visually via a laptop computer. Each word belonged to a single grammatical category. Further, words were matched for initial sound and approximate number of syllables. The results indicated that adults who stutter exhibited significantly greater stuttering frequency on content words when presented in isolation (p = 0.018). It was conjectured that the responsible factor contributing to differences in stuttering frequency in adults who stutter resides in word frequency disparities between the two classes of words categories. That is, because the function words are limited in number and are used frequently, repeated use on the part of adults who stutter may lead to a generalized adaptation effect for function words and hence reduced stuttering frequency (as compared with content words).     

Constancy of interstress intervals in the fluent speech of people who stutter during adaptation trials.

The constancy of interstress intervals (ISIs) was studied in the fluent speech of 2 people who stutter during five adaptation trials. Counter to prediction, ISI constancy did not improve as an accompaniment to the reduction of stuttering from Readings 1-5. Overall, the subjects' ISIs were substantially more variable in duration than those of 2 nonstutterers. This was accounted for by the subjects' unusually long ISIs in utterances that placed greater demands on speech motor control processes. Implications for impairment source factors in stuttering are discussed.     

Reliability of speech naturalness ratings of stuttered speech during treatment.

This study evaluated the reliability with which relatively sophisticated and unsophisticated judges used a 9-point scale to rate the speech naturalness of speech samples from 10 clients in a treatment program for stuttering that employed prolonged speech. Judges rated repeated speech samples from different speakers during various phases of the program. Different groups of sophisticated and unsophisticated judges made ratings at either 15 sec, 30 sec, or 60 sec intervals while listening to the samples. Of the reliability indices, intraclass correlations were significantly higher for sophisticated judges although the consistency and agreement of unsophisticated judges were generally equivalent to that of sophisticated judges. Both agreement scores and intraclass correlations were higher when ratings were made at 60 sec rather than 30 sec intervals. The predominant variable that influenced judgement reliability appeared to be differences among the subjects. The methodology partially replicated Martin, Haroldson, and Triden's (1984) initial investigation on the use of this scale. However, the levels of intra- or interjudge reliability in this study were lower than the levels achieved by Martin et al.'s judges. There were important differences between the Martin et al. study and this one that may account for the findings, and these are discussed.     

Telehealth delivery of the Camperdown Program for adults who stutter: a phase I trial.

PURPOSE: This Phase I trial investigated the viability of telehealth delivery of the Camperdown Program with adults who stutter. This program involves speech restructuring. METHOD: All treatment was conducted remotely with participant-clinician contact occurring by telephone and e-mail. RESULTS: Ten adults completed the program. The group showed an 82% reduction in stuttering frequency immediately after treatment and a 74% reduction 6 months after treatment. However, there was significant individual variation in response to the program. CONCLUSION: These preliminary data suggest that telehealth Camperdown has the potential to provide efficacious treatment for clients who do not have access to traditional face-to-face treatment.     

Stuttering and speech naturalness: audio and audiovisual judgments.

Unsophisticated raters, using 9-point interval scales, judged speech naturalness and stuttering severity of recorded stutterer and nonstutterer speech samples. Raters judged separately the audio-only and audiovisual presentations of each sample. For speech naturalness judgments of stutterer samples, raters invariably judged the audiovisual presentation more unnatural than the audio presentation of the same sample; but for the nonstutterer samples, there was no difference between audio and audiovisual naturalness ratings. Stuttering severity ratings did not differ significantly between audio and audiovisual presentations of the same samples. Rater reliability, interrater agreement, and intrarater agreement for speech naturalness judgments were assessed.     

Second formant transitions in fluent speech of persistent and recovered preschool children who stutter

This study investigated frequency change and duration of the second formant (F2) transitions in perceptually fluent speech samples recorded close to stuttering onset in preschool age children. Comparisons were made among 10 children known to eventually persist in stuttering, 10 who eventually recovered from stuttering, and 10 normally fluent controls. All were enrolled in the longitudinal Stuttering Research Project at the University of Illinois. Subjects fluently repeated standard experimental sentences. The same 36 perceptually fluent target segments (syllables embedded in words) from each subject's repeated sentences were analyzed. The syllables were divided into three phonetic categories based on their initial consonant: bilabial, alveolar, and velar placement. The frequency change and duration of F2 transitions were analyzed for each of the target CV segments. F2 transition onset and offset frequencies and their interval (duration) were measured for each utterance. Data indicate that near stuttering onset, children whose stuttering eventually persisted demonstrated significantly smaller frequency change than that of the recovered group. It is suggested that the F2 transitions should continue to be investigated as a possible predictor of stuttering pathways. LEARNING OUTCOMES: (1) Readers will learn about studies regarding second formant transition related to stuttering. (2) Readers will learn about differences between children who persist in stuttering and those who recover from stuttering. (3) Readers will learn about research concerned with early identification of risk criteria in persistent stuttering.