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.     

An analysis of speech disfluencies in down''s syndrome and in normally intelligent subjects

Spontaneous speech samples were obtained from 19 institutionalized mongoloids and from 19 normally intelligent individuals. All subjects were evaluated by a panel of speech pathologists to be nonstutterers. Subjects' speech samples were analyzed to determine (a) frequency of occurance of seven disfluency categories per 100 words spoken, (b) the proportion of each category in the total number of disfluencies. Statistically significant differences indicated that the mongoloids were more disfluent both absolutely and relatively, on categories that have been regarded as most typical to speech of stutterers. Interpretations were made to reflect on factors which may enhance the high prevalence of stuttering among Down's Syndrome patients.     

Disfluencies in cluttered speech

The purpose of this study was to examine the nature and frequency of occurrence of disfluencies, as they occur in singletons and in clusters, in the conversational speech of individuals who clutter compared to typical speakers. Except for two disfluency types (revisions in clusters, and word repetitions in clusters) nearly all disfluency types were virtually indistinguishable in frequency of occurrence between the two groups. These findings shed light on cluttering in several respects, foremost of which is that it provides documentation on the nature of disfluencies in cluttering. Findings also have implications for our understanding of the relationship between cluttering and typical speech, cluttering and stuttering, the Cluttering Spectrum Hypothesis, as well as the Lowest Common Denominator definition of cluttering. EDUCATIONAL OBJECTIVES: At the end of this activity the reader will be able to: (a) identify types of disfluency associated with cluttered speech; (b) contrast disfluencies in cluttered speech with those associated with stuttering; (c) compare the disfluencies of typical speakers with those of cluttering; (d) explain the perceptual nature of cluttering.     

Reaction time for voiced and whispered /a/ in stutterers and nonstutterers

Recent research reviewed in this article suggests that stutterers' inability to initiate phonation promptly could be a significant factor in the occurence of stuttering. Since stuttering is either completely absent or markedly reduced in frequency during whisper, the present study tested the hypothesis that stutterers do not significantly differ from nonstutterers in reaction time (RT) for the initiation of whispered/a/, whereas the two groups differ significantly in RT for the initiation of voiced /a/. Ten adult stutterers and an equal number of comparable nonstutterers produced prolonged versions of the vowel /a/ using voice and whisper in response to tone stimuli. The results showed that stutteres and nonstutterers did not differ in RT for either voiced or whispered /a/. The stutterers, however, exhibited significantly longer RT to produce voiced /a/ than whispered /a/.     

Stuttering and anxiety: The difference between stutterers and nonstutterers in verbal apprehension and physiologic arousal during the anticipation of speech and non-speech tasks

To test if stressful anticipation of speech situations is a factor in eliciting stuttering behavior, the difference between 24 stutterers and 24 nonstutterers in verbal apprehension and physiologic activity was studied before and during speech tasks (reading and conversation), and nonspeech tasks (motor and intelligence task).Results indicate that the difference between stutterers and nonstutterers mainly were restricted to anxiety ratings assessed after each task. Heart rate, vasomotor responses, and electrodermal activity recorded before and during speech tasks were higher compared with the physiologic activity before and during nonspeech tasks but, unexpectedly, this was also the case for nonstutterers. It is concluded that stuttering is not elicited by anxiety.     

Adaptation effect in nonfluent speech behavior of controlled stutterers and nonstutterers

The adaptation effect in stuttering behavior has received considerable attention. Adaptation effect is defined as the reduction in the frequency of nonfluencies in the speech of subjects during successive readings of the same passage. The objective of this investigation was to assess the adaptation effect of nonfluent speech behavior of controlled stutterers and nonstutterers. The subjects included 35 controlled stutterers and 35 nonstutterers matched for factors of sex, grade level, and age. Results suggest a significant mean difference between the number of nonfluencies between trials of controlled stutterers with evidence of adaptation in the speech of nonstutterers. Nonstutterers demonstrate significant mean differences in nonfluencies among replicated testing occasions. Findings of this investigation suggest that both controlled stutterers and nonstutterers demonstrate similar adaptation regarding their nonfluent speech behavior. Issues and import for future research are offered.     

Characteristics of stuttering-like disfluencies in Dutch-speaking children

The purpose of this study was to compare the characteristics of stuttering-like disfluencies in a group of native Dutch-speaking children who stutter (n = 693), with a group of normally fluent children (n = 79). Methods involved the observation of stuttering-like disfluencies in participants’ conversational speech samples (total 77,200 words), particularly the frequency, duration and physical tension of instances of stuttering. Findings indicate that stuttering-like disfluencies exhibited by children who stutter are significantly more frequent, longer in duration and involve more physical tension when compared to those of normally fluent children. Furthermore, applying a criterion of 3% stuttering-like disfluencies to distinguish stuttering from normally fluent children resulted in a high degree of sensitivity (0.9452) and specificity (0.9747). Results were taken to suggest that characteristics of stuttering-like disfluencies of Dutch-speaking children are similar to those of English-speaking children and that talker group membership criteria for childhood stuttering can reasonably be extrapolated from the Dutch to the English language and vice versa.

Educational objectives: The reader will be able to: (1) describe characteristics of stuttering-like disfluencies, (2) define properties such as frequency, duration and physical tension for stuttering children and normally fluent children, and (3) make use of data on sensitivity and specificity of the criterion of 3% stuttering-like disfluencies to distinguish stuttering and normally fluent children.     

Acquired stuttering following right frontal and bilateral pontine lesion: a case study

We report neurological information and experimental data regarding acquired neurogenic stuttering in a 57-year-old male following ischemic lesion to the orbital surface of the right frontal lobe and the pons. The experimental data consist of stuttering frequency measures under various conditions that are well known to enhance fluency in most individuals with developmental stuttering. Specifically, we report data for adaptation, unison reading, delayed auditory feedback (DAF), and frequency altered feedback (FAF). This work is the first published report of such a comprehensive examination of a variety of fluency-enhancing conditions in acquired stuttering. The patient read six 200-word texts under different conditions: Six solo readings (Text 1), five unison readings followed by five solo readings (Text 2), five readings with non-altered auditory feedback (Text 3), five readings with 50 ms delayed auditory feedback (Text 4), five readings with increased FAF (Text 5), and five readings with decreased FAF (Text 6). Results indicate that, unlike the typical situation for developmental stuttering, this individual with acquired neurogenic stuttering did not show increased fluency during an adaptation paradigm or under unison, DAF, and FAF conditions. We discuss possible implications of these findings and emphasize the need for further research on acquired neurogenic stuttering.     

Parkinsonian speech disfluencies: effects of L-dopa-related fluctuations

The excess dopamine theory of stuttering (Wu et al., 1997) contends that stuttering may be related to excess levels of the neurotransmitter dopamine in the brain. As Parkinson's disease (PD) patients commonly exhibit changes in dopamine levels accompanied by changes in motor performance, the present study examined disfluency in PD patients to gain information on the role of dopamine in speech disfluencies. Nine PD patients with no history of developmental stuttering were recorded once before and twice after taking their morning medication (on separate days). They read a passage and produced a monologue. Within-word and overall speech disfluencies were calculated at each recording. Through motor testing, it was inferred that participants had relatively low dopamine levels before taking medication, and relatively high dopamine levels after taking medication. There were no group changes in disfluency levels when the low-dopamine and high-dopamine states were compared. There were, however, significant differences in percent disfluencies between the PD participants and age-matched controls. The results of this study do not strongly support the excess dopamine theory of stuttering. Rather, the disfluency changes exhibited by individual participants support a hypothesis that speech disfluencies may be related to increases or decreases in dopamine levels in the brain. EDUCATIONAL OBJECTIVES: The reader will learn about: (1). the characteristics of disfluent speech exhibited by speakers with Parkinson's disease. (2). The effect of L-dopa based medications on disfluencies of Parkinsonian speakers. (3). The complex role brain dopamine levels may play in disfluent speaking behavior.     

Vocal changes in stutterers and nonstutterers when speaking to children

Within the last few years, considerable attention has been devoted to the possibility that the amelioration of stuttering in many novel speaking conditions is a function of vocal changes with or without accompanying modifications in prosodic expression. These formulations have made reference primarily to conditions in which stutterers were induced into one or another novel speech pattern by an external stimulus such as masking noise, a rhythmic cue, or by instructions to sing, or read in unison with another speaker. In contrast, far less attention has been paid to other ameliorative conditions that lack a novel external stimulus or special instructions that direct the stutterer to speak in some unique manner. Speaking or reading to a child is an example of this latter type of condition. The present study was conducted to see if nine adult stutterers and a matched group of nonstutterers would evince vocal changes as they read aloud to another adult, a child, and a child and adult together. There was also a fourth control condition wherein the subjects read to one of the experimenters. Dependent measures of disfluency and stuttering, fundamental frequency, fundamental frequency deviation, fluent reading rate, and peak vocal sound pressure level were made and treated statistically. The major findings of this study indicated that, relative to the control condition, both subject groups exhibited several vocal changes when reading to a child alone and to a child and adult together. In addition, the stutterers experienced a reduction in disfluency, but only when reading to the child alone. The normal speakers exhibited too few disfluencies in the control condition for any meaningful change to occur in that dependent variable. The fact that the stutterers evinced vocal changes in both experimental conditions but a significant drop in disfluency in just one bears importantly on hypotheses that emphasize vocal changes in conditions that ameliorate stuttering.     

Profiles of stutterers' and nonstutterers' affective, cognitive, and behavioral communication attitudes

The purposes of this investigation were 1) to profile the affective, cognitive, and behavioral attitudinal dimensions of stutterers' and nonstutterers' communication attitudes and 2) to describe membership characteristics of each profile. To this end, 76 stutterers and 81 nonstutterers completed the Inventory of Communication Attitudes. This self-report inventory obtained ratings of different types of speaking situations, using five response scales reflecting behavioral, affective, and cognitive aspects of attitudes. Exploratory cluster analysis identified six attitudinal clusters or profiles. Some profiles were more typical either of stuttering respondents or of nonstuttering respondents, whereas one profile reflected attitudes of proportionately equal numbers of stutterers and nonstutterers. Examination of profile membership characteristics revealed two significant discriminators, classification as a stutterer or nonstutterer and an overall speech rating. Nondiscriminatory characteristics included sex, age, education, therapy experiences, stuttering severity self-rating, onset of stuttering, total therapy time, current therapeutic status, and familial history.     

Speech and bimanual hand organization in adult stutterers and nonstutterers

A multivariate approach was used to investigate the relationship between speech fluency and bimanual handwriting in right-handed male stutterers and nonstutterers. Handedness was determined by the Harris Test of Lateral Dominance. Subjects were required to write the numbers 1 through 12 simultaneously, as quickly as possible. Speech measures were derived from the Stuttering Severity Instrument and from a reading passage. Stutterers performed more poorly than nonstutterers on all speech measures. There were no differences in bimanual handwriting performance for the dominant hand. However, stutterers performed more poorly than nonstutterers in nondominant handwriting. There were no relationships between speech measures and bimanual handwriting for stutterers or nonstutterers. Some stutterers performed better on the handwriting task than did some nonstutterers. It is suggested that disorganization in interhemispheric integration functions may be a more fundamental problem in stuttering than is incomplete cerebral dominance.     

Disfluent speech associated with brain damage

The frequency and type of disfluencies in the spontaneous speech of 15 people with Broca's aphasia and right hemiplegia was studied. Two aged-matched control groups (15 nonaphasic stroke patients with left hemiplegia and 15 normals) were also studied. The frequency of disfluencies in the speech of aphasics was three times greater than that in the speech of either control group. However, most of the disfluencies uttered by aphasics were of the types commonly found in speech of normals.     

Motor Performance of Stutterers and Nonstutterers on Timing and Force Control Tasks

Recently it has been suggested that speech and manual timing tasks share a common central process (Franz, Zelaznik, & Smith, 1992): Because stuttering is thought to be related to deficits in motoric processes such as timing, stutterers (n = 15) were compared with a set of age-, education-, and sex-matched nonstutterers on timing and isometric force-production tasks. In the timing tasks, subjects flexed and extended the right index finger at the metacarpophalangeal joint at cycle durations of 600, 500, 400, 300, and 200 ms. In the force-production tasks, subjects generated isometric forces to match target force levels displayed on a cathode-ray tube (CRT) screen. There were five levels of force, ranging from.11 to 7.85 newtons. Overall, there were no differences in timing and force-production performance between stutterers and nonstutterers. These results are similar to those obtained recently by Hulstijn, Summers, van Lieshout, and Peters (1992). We suggest that stuttering is not characterized by a general deficit in rhythmic timing. Instead, the motor deficit associated with stuttering should be viewed as speech specific.     

Disfluency clusters in speakers with and without neurogenic stuttering following traumatic brain injury

PurposeAnalyze the characteristics and rate of disfluency clusters in adults with and without neurogenic stuttering after traumatic brain injury (TBI).MethodTwenty adults with TBI participated in this study, including 10 with neurogenic stuttering (Group B) and 10 without -stuttering (Group A). Disfluency clusters in speech samples were classified into three types: Stuttering-like (SLD), other (OD), and mixed (MIX).ResultsSpeakers with and without neurogenic stuttering produced the same mean number of disfluency clusters. In addition, the mean length of clusters did not differ between these speaker groups although the longest clusters did. The most frequently occurring cluster type for people with neurogenic stuttering was MIX and OD for people without stuttering. Although the speakers in Group A produced stuttering-like disfluencies, these never occurred together to form a SLD type cluster. For Group B, the starter units of the clusters were usually stuttering-like disfluencies, while for Group A, the starter units were mostly interruptions.ConclusionsCompared to non-stuttering speakers, stuttering after TBI did not increase the number of clusters, but rather lengthened them. In speakers with neurogenic stuttering, the number and length of clusters were related to the manifestation of other communication deficits, not to the frequency of stuttering-like disfluencies. Still, SLD clusters occurred only in those people with neurogenic stuttering. These findings raise questions about the nature of both neurogenic stuttering and the dynamics of disfluency clustering.     

Operant techniques used in stuttering therapy: A review

This article reviews research concerning the use of operant conditioning in stuttering therapy, and discusses the clinical implications of this literature. In order to be considered for this review, a report had to treat the findings of research specifically designed to use operant conditioning in the manipulation of speech disfluency. This body of experimental literature clearly indicates that operant management techniques can effectively reduce stuttering with punishment of disfluencies producing more notable results than reinforcement of fluent responses. Operant conditioning is an effective means of modifying stuttering behavior and should be more visible in terms of procedures used by speech therapists.     

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

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

Motor Performance of Stutterers and Nonstutterers on Timing and Force Control Tasks

Recently it has been suggested that speech and manual timing tasks share a common central process (Franz, Zelaznik, & Smith, 1992). Because stuttering is thought to be related to deficits in motoric processes such as timing, stutterers (n = 15) were compared with a set of age-, education-, and sex-matched nonstutterers on timing and isometric force-production tasks. In the timing tasks, subjects flexed and extended the right index finger at the metacarpophalangeal joint at cycle durations of 600, 500, 400, 300, and 200 ms. In the force-production tasks, subjects generated isometric forces to match target force levels displayed on a cathode-ray tube (CRT) screen. There were five levels of force, ranging from .11 to 7.85 newtons. Overall, there were no differences in timing and force-production performance between stutterers and nonstutterers. These results are similar to those obtained recently by Hulstijn, Summers, van Lieshout, and Peters (1992). We suggest that stuttering is not characterized by a general deficit in rhythmic timing. Instead, the motor deficit associated with stuttering should be viewed as speech specific.