Effects of delayed auditory feedback on acquired stuttering following head injury

This study examined the effects of Delayed Auditory Feedback (DAF) with three cases of acquired stuttering following head injury. To determine the effects of DAF on stuttering behavior a multiple baseline design across three speaking tasks was employed. All subjects reduced stuttering with application of DAF. Stuttering behavior on untreated tasks continuing in baseline was not affected by DAF. When treatment was applied to the untreated tasks, stuttering events decreased for all three subjects. Results indicate DAF has potential as a treatment procedure with cases of acquired stuttering in a way similar to cases of developmental stuttering.     

The separate and combined effects of GSR biofeedback and delayed auditory feedback on stuttering: A preliminary study

The separate and combined effects of galvanic skin response biofeedback low wave amplitude self regulation (GSR LW) and amplified delayed auditory feedback (DAF) upon stuttering dysfluency are examined. Two college age male stutterers who were seen on an intensive longitudinal basis were the subjects in this study.Results suggest that GSR LW, when it is accomplished, functions to moderately but significantly reduce stuttering dysfluency compared to no GSR biofeedback. This effect does not noticeably dissipate over time. There occurred a marked and sustained reduction in stuttering dysfluency under DAF compared to no DAF conditions. Without separating accomplished and not accomplished GSR LW, there occurred slightly but not statistically significantly fewer blocks under the combined DAF-GSR LW condition than under DAF alone. Nevertheless, it does seem likely, considering these findings overall, that when GSR LW is accomplished, the fluency facilitating effect of its simultaneous combination with DAF is additive i.e., greater than either alone. Possible theoretical and therapeutic implications are discussed.     

The use of a portable delayed auditory feedback unit in stuttering therapy

A portable on-the-body delayed auditory feedback was used in the establishment and transfer modes of fluent speech in a stutterer while he was on the Monterey Fluency Program. The performance of the client was compared with a “standard” population of stutterers. The portable DAF was comparable to the larger DAF in establishment and superior in transfer with minimal behavioral and technical problems. Use and potential value of the portable DAF in transfer and maintenance phases of therapy are discussed.     

Adaptation to delayed auditory feedback

Delayed auditory feedback disrupts the production of speech, causing an increase in speech duration as well as many articulatory errors. To determine whether prolonged exposure to delayed auditory feedback IDAFI leads to adaptive compensations in speech production, 10 subjects were exposed in separate experimental sessions to both incremental and constantdelay exposure conditions. Significant adaptation occurred for syntactically structured stimuli in the form of increased speaking rates. After DAF was removed, aftereffects were apparent for all stimulus types in terms of increased speech rates. A carry-over effect from the first to the second experimental session was evident as long as 29 days after the first session. The use of strategies to overcome DAF and the differences between adaptation to DAF and adaptation to visual rearrangement are discussed.     

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.     

Twins' reactions to delayed auditory feedback

10 pairs of identical and 10 pairs of fraternal twins, matched by age, spoke under conditions of 0.0-, 100-, 200-, 300-, 400-, and 500-msec. delayed auditory feedback. Length of spoken passages was controlled. Product-moment and intraclass correlations were calculated for speaking times and disfluencies. Significant Pearson rs for times were noted at 0.0 and 300 msec. for both groups and at 100, 200, and 400 msec. for identical twins, while fraternal twins' times were significantly correlated at 500 msec. Difference scores were significantly correlated at 100, 200, 300, and 400 msec. for identical twins. Disfluencies were significantly correlated for identical twins at 400 msec. Data were combined with those of Timmons' (1969) study, increasing subjects to 21 pairs per group. Intraclass correlations supported the contention that responses of identical twin pairs to delayed auditory feedback were more highly correlated than those for fraternal twin pairs.     

Augmented visual, auditory, haptic, and multimodal feedback in motor learning: A review

It is generally accepted that augmented feedback, provided by a human expert or a technical display, effectively enhances motor learning. However, discussion of the way to most effectively provide augmented feedback has been controversial. Related studies have focused primarily on simple or artificial tasks enhanced by visual feedback. Recently, technical advances have made it possible also to investigate more complex, realistic motor tasks and to implement not only visual, but also auditory, haptic, or multimodal augmented feedback. The aim of this review is to address the potential of augmented unimodal and multimodal feedback in the framework of motor learning theories. The review addresses the reasons for the different impacts of feedback strategies within or between the visual, auditory, and haptic modalities and the challenges that need to be overcome to provide appropriate feedback in these modalities, either in isolation or in combination. Accordingly, the design criteria for successful visual, auditory, haptic, and multimodal feedback are elaborated.     

Speech production mechanisms in aphasia: A delayed auditory feedback study

Data collected from a delayed auditory feedback (DAF) study conducted by F. Boller, P. B. Vrtunski, Y. Kim, and J. L. Mack (1978, Cortex, 14, 212–226) were reanalyzed to determine if speech quality measures which were significantly affected during DAF could be operationalized and to ascertain which type of errors are responsible for the judgement. A second goal of this study was to determine if Conduction aphasics were relatively spared under conditions of DAF, as has been shown in previous studies. Twenty aphasic patients and ten controls were presented with several speech production tasks under two delay conditions and two simultaneous feedback conditions. Results indicated that only the category of vowel length produced a significant number of errors, suggesting that DAF affects articulatory implementation. Conduction aphasics showed the least effect of all the groups. These results support Wernicke's and Geschwind's model, in which Conduction aphasics have a disconnection between the sensory and motor images of words. In contrast, Broca's aphasics were the most affected group under DAF, suggesting that a major component of their disorder is phonetic in nature.     

To speak with an accent: Effects of nasal distortion on stuttering under delayed auditory feedback

The main question in this study was whether Ss stuiter less under DAF when speaking with an accent such as a nasal twang. The hypothesis was verified: A group of 21 Ss stuttered less under DAF when speaking with a nasal accent than when speaking normally. This effect was shown to be due to: (1) The change in the acoustic output as a result of speaking with the accent. A passively produced distortion of the returning feedback (after Held, 1961), which was similar to the actively articulated nasal accent, also caused the Ss to stutter less than normally. (2) Paying less attention to the disruptive feedback. The Ss were shown to pay less attention to nasal feedback, probably because producing a nasal accent requires greater attention to articulation. These results were not due to a reduction in the intelligibility of the nasal feedback, which was just as intelligible as the S’s normal voice, even in noise. The significance of these findings for general theories of DAF and pathological stuttering were discussed.     

A preliminary report of oral tactile sensation and responses to delayed auditory feedback

Individual speakers vary widely in their reactions to delayed auditory feedback. In this pilot investigation, 21 adults with normal speech and hearing completed standardized readings under simultaneous and 200-msec. delayed auditory feedback. Minimally and maximally affected speakers were identified. Vibrotactile thresholds were obtained from the tongue and thenar eminence of the right hand for a group of five minimally and a group of five maximally affected speakers. Analysis showed that vibrotactile thresholds were lower (more sensitive) at both assessment sites for the group of maximally affected speakers. This finding is discussed in relation to the possible implications of heightened tactile sensitivity in the control of speech under delayed auditory feedback.     

Portable delayed auditory feedback device: A preliminary report

This writing is a preliminary report describing a prototype of a portable delayed auditory feedback device called the DYSTECH 1000. This writing and our observations are presented to stimulate review and feedback by our colleagues of the DYSTECH 1000 as a clinical and generalization tool.     

Efficacy of delayed auditory feedback for treating cluttering: Two case studies

Two clutterers were treated with similar preplanned delayed auditory feedback (DAF) procedures, using probe samples in which the DAF was not present to measure treatment efficacy. Whereas both clients met established fluency criteria during treatment, both clutterers had difficulty transferring gains to probe sessions—one more than the other. Differences in results of DAF treatment are discussed from the perspectives of differences in cluttering severity, coexisting disorders, and supplementary clinical techniques.     

Altered auditory feedback and the treatment of stuttering: a review

Several authors have suggested that devices delivering altered auditory feedback (AAF) may be a viable treatment for adults and children who stutter. This paper reviews published, peer reviewed journal papers from the past 10 years that investigate the effect of AAF during different speaking conditions, tasks and situations. A review of that literature indicates that considerable experimental evidence and limited Phase 1 treatment outcome evidence has been accumulated about the effect of AAF on the speech of people who stutter. However, critical knowledge about the effect of AAF during conversational speech and in everyday speaking situations is missing. Knowledge about how to determine the correct levels of AAF for individuals, and the characteristics of those likely to benefit from AAF, also needs to be established. At present there is no reason to accept a recent suggestion that AAF devices would be a defensible clinical option for children. In general device development and availability has occurred at a faster pace than clinical trials research. EDUCATIONAL OBJECTIVES: After reading this paper readers should be able to: (1) describe what altered auditory feedback is and common ways the speech signal is altered in stuttering; (2) describe the effects of AAF on the speech of adults who stutter; (3) provide a critical analysis of the literature in the area of AAF and stuttering.     

Oral/manual motor reaction times and delayed auditory feedback disturbances among normally speaking females

Research has indicated that stuttering and nonstuttering groups can be differentiated on the basis of certain motor reaction time variables. This study evaluated the manual and oral reaction times to a 1000 Hz stimulus tone in 39 normally speaking college females. Speech disfluencies of the subjects (Ss) were identified by a four-judge panel and correlated with reaction time scores. Although no significant correlations were obtained, it was observed that Ss with faster oral and manual reaction times tended to have more disfluencies under delayed auditory feedback.