Identifying the onset and offset of stuttering events

Reliability of judgments of stuttering-related variables: The effect of language familiarity

Previous studies demonstrate mixed results and some methodological limitations regarding judges' ability to reliably assess stuttering-related variables in an unfamiliar language. The present study examined intra- and inter-rater reliability for percent syllables stuttered (%SS), stuttering severity (SEV), syllables per minute (SPM), and speech naturalness (NAT) when English-speaking judges viewed speech samples in English and in a language with which they had no or minimal familiarity (Spanish). Over two time periods, 21 judges viewed eight videos of four bilingual persons who stutter. Data were analyzed for relative and absolute intra- and inter-rater reliability as well as for an effect of language on time period differences. Intra- and inter-rater relative reliability were good or excellent for all measures in both languages, with the exception of inter-rater relative reliability for NAT in both languages and %SS in Spanish. Intra-rater absolute reliability was acceptable in both languages for NAT and SEV and unacceptable in both for SPM and %SS. Inter-rater absolute reliability in both languages was unacceptable for all measures, even with judges with the same training. There was a clinically significant effect of language on %SS scores, but, despite a statistically significant effect of language for SPM and SEV, the differences were not clinically significant. Results indicate that reliability across and within languages varies by measure and is impacted by intra- vs. inter-rater reliability, relative vs. absolute reliability, and language familiarity. Modifications in training may be able to address some of the limitations found, particularly with regard to SPM and NAT.

How Stuttering Develops: The Multifactorial Dynamic Pathways Theory

Purpose

We advanced a multifactorial, dynamic account of the complex, nonlinear interactions of motor, linguistic, and emotional factors contributing to the development of stuttering. Our purpose here is to update our account as the multifactorial dynamic pathways theory.

Method

We review evidence related to how stuttering develops, including genetic/epigenetic factors; motor, linguistic, and emotional features; and advances in neuroimaging studies. We update evidence for our earlier claim: Although stuttering ultimately reflects impairment in speech sensorimotor processes, its course over the life span is strongly conditioned by linguistic and emotional factors.

Results

Our current account places primary emphasis on the dynamic developmental context in which stuttering emerges and follows its course during the preschool years. Rapid changes in many neurobehavioral systems are ongoing, and critical interactions among these systems likely play a major role in determining persistence of or recovery from stuttering.

Conclusion

Stuttering, or childhood onset fluency disorder (Diagnostic and Statistical Manual of Mental Disorders, 5th edition; American Psychiatric Association [APA], 2013), is a neurodevelopmental disorder that begins when neural networks supporting speech, language, and emotional functions are rapidly developing. The multifactorial dynamic pathways theory motivates experimental and clinical work to determine the specific factors that contribute to each child's pathway to the diagnosis of stuttering and those most likely to promote recovery.

Event- and interval-based measurement of stuttering: a review

BACKGROUND

Event- and interval-based measurements are two different ways of computing frequency of stuttering. Interval-based methodology emerged as an alternative measure to overcome problems associated with reproducibility in the event-based methodology. No review has been made to study the effect of methodological factors in interval-based absolute reliability data or to compute the agreement between the two methodologies in terms of inter-judge, intra-judge and accuracy (i.e., correspondence between raters' scores and an established criterion).

AIMS

To provide a review related to reproducibility of event-based and time-interval measurement, and to verify the effect of methodological factors (training, experience, interval duration, sample presentation order and judgment conditions) on agreement of time-interval measurement; in addition, to determine if it is possible to quantify the agreement between the two methodologies

METHODS & PROCEDURES

The first two authors searched for articles on ERIC, MEDLINE, PubMed, B-on, CENTRAL and Dissertation Abstracts during January-February 2013 and retrieved 495 articles. Forty-eight articles were selected for review. Content tables were constructed with the main findings.

MAIN CONTRIBUTION

Articles related to event-based measurements revealed values of inter- and intra-judge greater than 0.70 and agreement percentages beyond 80%. The articles related to time-interval measures revealed that, in general, judges with more experience with stuttering presented significantly higher levels of intra- and inter-judge agreement. Inter- and intra-judge values were beyond the references for high reproducibility values for both methodologies. Accuracy (regarding the closeness of raters' judgements with an established criterion), intra- and inter-judge agreement were higher for trained groups when compared with non-trained groups. Sample presentation order and audio/video conditions did not result in differences in inter- or intra-judge results. A duration of 5 s for an interval appears to be an acceptable agreement. Explanation for high reproducibility values as well as parameter choice to report those data are discussed.

CONCLUSIONS & IMPLICATIONS

Both interval- and event-based methodologies used trained or experienced judges for inter- and intra-judge determination and data were beyond the references for good reproducibility values. Inter- and intra-judge values were reported in different metric scales among event- and interval-based methods studies, making it unfeasible to quantify the agreement between the two methods.

Effects of time-interval judgement training on real-time measurement of stuttering

The purpose of this study was to investigate whether a previously developed interval-based training program could improve judges' stuttering event judgments. Two groups of judges made real-time stuttering event judgments (computer-mouse button presses) in 3 to 6 trials before the response-contingent judgment training program and in another 3 to 6 trials after training, for recordings of 9 adults who stuttered. Their judgments were analyzed in terms of number of stuttering events, duration of stuttering, and 5-s intervals of speech that could be categorized as judged (or not judged) to contain stuttering. Results showed (a) changes in the amount of stuttering identified by the judges; (b) improved correspondence between the judges' identifications of stuttering events and interval-based standards previously developed from judgments made by experienced, authoritative judges; (c) improved correspondence between interval-based analyses of the judges' stuttering judgments and the previously developed standards; (d) improved intrajudge agreement; (e) improved interjudge agreement; and (f) convergence between the 2 judge groups, for samples and speakers used during training tasks and also for other speakers. Some implications of these findings for developing standardized procedures for the real-time measurement of stuttering are discussed.

Guidelines for documentation of treatment efficacy for young children who stutter

The pressing need to document treatment efficacy for young children who stutter is discussed. Guidelines for such documentation are suggested and illustrated. Measures for verifying treatment effects in four realms are delineated: (a) conditions of documentation, (b) dependent variables to be measured, (c) establishment of treatment integrity, and (d) verification of the relationship between treatment and outcome. Illustrations of the application of the suggested guidelines are presented for 2 children.

The effects of fluency-evoking conditions on voicing onset types in persons who do and do not stutter

Voicing onset changes between control conditions and three fluency-evoking conditions (choral reading [CHORAL], delayed auditory feedback [DAF], and noise [NOISE]) were studied in 12 persons who do not stutter and 10 who do stutter. Voicing onsets were distinguished physiologically using airflow prior to voicing, with zero airflow prevoicing categorized as hard and the rest as breathy. Persons who stutter were more fluent under all fluency-evoking conditions than control conditions. Speaking under fluency-evoking conditions did not significantly increase the overall proportion of breathy onsets from control conditions for either group. However, looking only at hard onsets in the control condition, we found that both groups changed significantly more to breathy (p = 0.001) under CHORAL and NOISE. In persons who stutter, onset type was not associated with whether a word was produced fluently or dysfluently in the control condition. Also, no relationship was found between onsets changing to breathy under fluency-evoking conditions and onsets changing to fluent. The results suggest that although fluency-evoking conditions can modify some voicing onset behaviors, these modifications do not relate to improvements in fluency.

Modifications in aerodynamic variables by persons who stutter under fluency-evoking conditions

The purposes of this study were to (a) compare the effects of fluency-evoking conditions on aerodynamic variables in 10 persons who stutter with those previously reported for 12 individuals who do not stutter; (b) determine if any changes demonstrated in the amplitude and/or timing of aerodynamic variables were accounted for by changes in speech intensity; and (c) determine if any amplitude or timing changes in flow and intraoral pressure were related to improved fluency. The fluency-evoking conditions were choral reading (CR), metronome-pacing (MET), delayed auditory feedback (DAF), and noise (NOISE). From 8 words beginning with plosive consonants in CVC contexts read aloud in sentences, measures were made of 8 variables, including closure duration, amplitude and time to maximum airflow and intraoral pressure for initial plosives, and the duration and intensity of the following vowel. Speech rate was also computed. Only fluently produced target words from persons who stutter were analyzed. All persons who stutter showed improved fluency under all conditions. Both groups demonstrated significant (p < or = 0.006) condition effects for peak flow, vowel intensity, and pressure rise time. Thus, fluency-evoking conditions affected these variables regardless of speaker type. Both groups changed peak pressure in similar directions from baseline depending on condition, but not significantly for each group in the same conditions. Persons who stutter significantly increased speech rate for CR, DAF, and NOISE; and persons who do not stutter significantly decreased rate under DAF. The reported changes in peak pressure and peak flow could not be accounted for by changes in vowel intensity. Larger improvements in fluency occurred under conditions when peak flow and peak pressure values were decreased from baseline. Thus, variables that were modified by both groups when speaking under conditions were also the variables related to changes in fluency for the persons who stutter.

Identifying the authoritative judgments of stuttering: comparisons of self-judgments and observer judgments

Reliable and accurate stuttering measurement depends on the existence of unambiguous descriptions or exemplars of stuttered and nonstuttered speech. The development of clinically meaningful and useful exemplars, in turn, requires determining whether persons who stutter judge the same speech to be stuttered that other observers judge to be stuttered. The purpose of these experiments, therefore, was to compare stuttering judgements from several sources: 15 adults who stutter, judging their own spontaneous speech; the same adults who stutter, judging each other's speech; and a panel of 10 authorities on stuttering research and treatment. Judgments were mode under several conditions, including self-judgments made while the speaker was talking and self- and other-judgements made from recordings in continuous and interval formats. Results showed substantial differences in stuttering judgments across speakers, judges, and judgment conditions, but across-task comparisons were complicated by low self-agreement for many judges. Some intervals were judged consistently by all judges to be Stuttered or Nonstuttered, across multiple conditions, but many other intervals were either not assigned replicable judgments or were consistently judged to be Nonstuttered by the speaker who had produced them but were not assigned consistent judgments by other judges. The implications of these findings for stuttering measurement are considered.

Experimental investigation of the effects of frequency-altered auditory feedback on the speech of adults who stutter

A series of single-subject experiments evaluated the effects of frequency-altered auditory feedback (FAF) on the speech performance of four adult males who stutter. Using alterations of plus or minus one octave, FAF was compared with normal auditory feedback (NAF) in oral reading and spontaneous speech with measurements made of stuttered intervals, stutter-free speech rate, and speech naturalness. The effects of extended FAF conditions on spontaneous speech were also evaluated for two subjects who demonstrated a positive response to FAF. Results showed no consistencies across subjects in responses to FAF: One subject showed no response, another produced an initial temporary response, a third showed a deterioration in speech quality with minimal reductions in stuttering, and a fourth displayed substantial and sustained improvements in speech performance. Some implications of these findings for current research and theory about the relationship between stuttering and FAF are discussed.

Stuttering includes both within-word and between-word disfluencies

A growing practice divides stuttered disfluencies from normal disfluencies by defining the former as "within-word" and the latter as "between-word." After reviewing the available logical and empirical evidence, this note concludes that the unstated implications of a strong form of this definition (that no between-word disfluencies are stuttering and that all within-word disfluencies are stuttering) cannot currently be supported. A weaker form of this definition might prove useful for the definition and measurement of stuttering, but only if such a definition can be both internally consistent and consistent with available clinical and empirical information.