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

Impact of auditory feedback alterations in individuals with stuttering

INTRODUCTION

Electrophysiological evidence has reinforced the hypothesis that stuttering is associated with a deficit in modulation of the cortical auditory system during speech planning, contributing to an inefficient auditory feedback monitoring and, consequently, resulting in disfluencies.

OBJECTIVE

To verify the impact of auditory feedback modifications on the spontaneous speech of individuals with stuttering.

METHODS

Sixteen individuals, of both genders, aged 8-17 years and 11 months, with a diagnosis of persistent neurodevelopmental stuttering, were divided into two groups: Moderate Stuttering Group and Severe Stuttering Group. The testing procedures consisted of three stages: collection of identification data, audiological assessment and fluency evaluation of spontaneous speech in four auditory feedback conditions (non-altered, delayed, masked and amplified). The speech sample obtained in the non-altered feedback was considered the control; the others were considered as modified listening conditions.

RESULTS

Regarding the stuttering-like disfluencies, a statistically significant difference was observed in the intragroup analysis of the Moderate Stuttering Group between non-altered and masked auditory feedback (p = 0.042), as well as between non-altered and amplified (p = 0.042). There was a statistically significant difference in the Severe Stuttering Group for all auditory feedback modifications in relation to the non-altered (delayed p = 0.012, masked p = 0.025 and amplified p = 0.042). There was also a reduction in flows of syllables and words-per-minute in the Moderate Stuttering Group for the delayed auditory feedback, as compared to non-altered (p = 0.017 and p = 0.025, respectively).

CONCLUSION

The effect of delayed auditory feedback was favorable for the Severe Stuttering Group, promoting speech fluency. The conditions of masked and amplified auditory feedback resulted in speech benefits in both groups, decreasing the number of stuttering-like disfluencies. The speech rate was not impaired by any listening condition analyzed.

What works for whom? Multidimensional individualized stuttering therapy (MIST)

PURPOSE

This study reports outcomes from a stuttering therapy approach that combines value and awareness-based elements from Acceptance and Commitment Therapy (ACT) with those of stuttering and speech modification interventions. The approach, entitled Multidimensional Individualized Stuttering Therapy (MIST), includes a combined clinician and client selection of factors across five areas: 1) general breathing patterns and body tension, 2) breathing patterns during speech production, 3) vocal features in speech production, 4) value and mindfulness-based strategies, and 5) general communication and/or presentation skills. The aims of this study were to evaluate whether the MIST a) reduces the impact of stuttering and stuttering severity, and b) has a positive impact on speaking ability, confidence in communication, avoidance-behavior, and quality of life.

METHOD

Eighteen adults, age 21-61 years took part in an A-B-A multiple case study design. Participants underwent a pre-clinic assessment phase, followed by 10 h of therapy over four sessions administered by an experienced speech-language therapist. Outcome measures examined both psychosocial and behavioral aspects of therapy three-, six- and twelve-months post-therapy.

RESULTS

Most participants chose elements from at least four of the five areas of focus. There was a significant reduction in the impact of stuttering at both 6- and 12-months post-therapy, with moderate (d = .71) to very large (d = 1.06) effect sizes. A strong association was found between overall satisfaction with MIST and improved speaking abilities. Moderate to strong associations were also found between experienced speaking abilities, confidence in communication, reduction in avoidance behaviors and improved quality of life.

DISCUSSION

Findings indicate that MIST can be effective in managing adult stuttering. The findings highlight the importance of shared decision making and personal considerations using flexible therapy approaches that integrate stuttering and speech modification interventions with value and awareness-based skills. The nature of a multidimensional individualized approach, as shown in this study, highlights the importance of adjusting the relative weighting of different subcomponents according to each individual's needs and goals.

CONCLUSION

MIST was shown to be efficacious in clinical settings and effective in real life settings. Findings were promising, despite a relatively small sample, and replication by other SLPs and with larger samples is warranted.

Anomalous morphology in left hemisphere motor and premotor cortex of children who stutter

Stuttering is a neurodevelopmental disorder that affects the smooth flow of speech production. Stuttering onset occurs during a dynamic period of development when children first start learning to formulate sentences. Although most children grow out of stuttering naturally, ∼1% of all children develop persistent stuttering that can lead to significant psychosocial consequences throughout one's life. To date, few studies have examined neural bases of stuttering in children who stutter, and even fewer have examined the basis for natural recovery versus persistence of stuttering. Here we report the first study to conduct surface-based analysis of the brain morphometric measures in children who stutter. We used FreeSurfer to extract cortical size and shape measures from structural MRI scans collected from the initial year of a longitudinal study involving 70 children (36 stuttering, 34 controls) in the 3-10-year range. The stuttering group was further divided into two groups: persistent and recovered, based on their later longitudinal visits that allowed determination of their eventual clinical outcome. A region of interest analysis that focused on the left hemisphere speech network and a whole-brain exploratory analysis were conducted to examine group differences and group × age interaction effects. We found that the persistent group could be differentiated from the control and recovered groups by reduced cortical thickness in left motor and lateral premotor cortical regions. The recovered group showed an age-related decrease in local gyrification in the left medial premotor cortex (supplementary motor area and and pre-supplementary motor area). These results provide strong evidence of a primary deficit in the left hemisphere speech network, specifically involving lateral premotor cortex and primary motor cortex, in persistent developmental stuttering. Results further point to a possible compensatory mechanism involving left medial premotor cortex in those who recover from childhood stuttering.

Stuttering Frequency, Speech Rate, Speech Naturalness, and Speech Effort During the Production of Voluntary Stuttering

PURPOSE

Voluntary stuttering techniques involve persons who stutter purposefully interjecting disfluencies into their speech. Little research has been conducted on the impact of these techniques on the speech pattern of persons who stutter. The present study examined whether changes in the frequency of voluntary stuttering accompanied changes in stuttering frequency, articulation rate, speech naturalness, and speech effort.

METHOD

In total, 12 persons who stutter aged 16-34 years participated. Participants read four 300-syllable passages during a control condition, and three voluntary stuttering conditions that involved attempting to produce purposeful, tension-free repetitions of initial sounds or syllables of a word for two or more repetitions (i.e., bouncing). The three voluntary stuttering conditions included bouncing on 5%, 10%, and 15% of syllables read. Friedman tests and follow-up Wilcoxon signed ranks tests were conducted for the statistical analyses.

RESULTS

Stuttering frequency, articulation rate, and speech naturalness were significantly different between the voluntary stuttering conditions. Speech effort did not differ between the voluntary stuttering conditions. Stuttering frequency was significantly lower during the three voluntary stuttering conditions compared to the control condition, and speech effort was significantly lower during two of the three voluntary stuttering conditions compared to the control condition.

CONCLUSIONS

Due to changes in articulation rate across the voluntary stuttering conditions, it is difficult to conclude, as has been suggested previously, that voluntary stuttering is the reason for stuttering reductions found when using voluntary stuttering techniques. Additionally, future investigations should examine different types of voluntary stuttering over an extended period of time to determine their impact on stuttering frequency, speech rate, speech naturalness, and speech effort.

Functional and Neuroanatomical Bases of Developmental Stuttering: Current Insights

Affecting 5% of all preschool-aged children and 1% of the general population, developmental stuttering-also called childhood-onset fluency disorder-is a complex, multifactorial neurodevelopmental disorder characterized by frequent disruption of the fluent flow of speech. Over the past two decades, neuroimaging studies of both children and adults who stutter have begun to provide significant insights into the neurobiological bases of stuttering. This review highlights convergent findings from this body of literature with a focus on functional and structural neuroimaging results that are supported by theoretically driven neurocomputational models of speech production. Updated views on possible mechanisms of stuttering onset and persistence, and perspectives on promising areas for future research into the mechanisms of stuttering, are discussed.

Rhythmic speech and stuttering reduction in a syllable-timed language

Speaking rhythmically, also known as syllable-timed speech (STS), has been known for centuries to be a fluency-inducing condition for people who stutter. Cantonese is a tonal syllable-timed language and it has been shown that, of all languages, Cantonese is the most rhythmic (Mok, 2009). However, it is not known if STS reduces stuttering in Cantonese as it does in English. This is the first study to investigate the effects of STS on stuttering in a syllable-timed language. Nineteen native Cantonese-speaking adults who stutter were engaged in conversational tasks in Cantonese under two conditions: one in their usual speaking style and one using STS. The speakers' percentage syllables stuttered (%SS) and speech rhythmicity were rated. The rhythmicity ratings were used to estimate the extent to which speakers were using STS in the syllable-timed condition. Results revealed a statistically significant reduction in %SS in the STS condition; however, this reduction was not as large as in previous studies in other languages and the amount of stuttering reduction varied across speakers. The rhythmicity ratings showed that some speakers were perceived to be speaking more rhythmically than others and that the perceived rhythmicity correlated positively with reductions in stuttering. The findings were unexpected, as it was anticipated that speakers of a highly rhythmic language such as Cantonese would find STS easy to use and that the consequent reductions in stuttering would be great, even greater perhaps than in a stress-timed language such as English. The theoretical and clinical implications of the findings are discussed.

An investigation of the effects of a speech-restructuring treatment for stuttering on the distribution of intervals of phonation

PURPOSE

The purpose of this study was to investigate whether stuttering reductions following the instatement phase of a speech-restructuring treatment for adults were accompanied by reductions in the frequency of short intervals of phonation (PIs). The study was prompted by the possibility that reductions in the frequency of short PIs is the mechanism underlying such reductions in stuttering.

METHOD

The distribution of PIs was determined for seven adults who stutter, before and immediately after the intensive phase of a speech-restructuring treatment program. Audiovisual recordings of conversational speech were made on both assessment occasions, with PIs recorded with an accelerometer.

RESULTS

All seven participants had much lower levels of stuttering after treatment but these were associated with reductions in the frequency of short PIs for only four of them. For the other three participants, two showed no change in frequency of short PIs, while for the other participant the frequency of short PIs actually increased.

CONCLUSIONS

Stuttering reduction with speech-restructuring treatment can co-occur with reduction in the frequency of short PIs. However, the latter does not appear necessary for this reduction in stuttering to occur. Thus, speech-restructuring treatment must have other, or additional, treatment agents for stuttering to reduce.

Comparação da leitura de escolares com gagueira em duas condições de escuta: habitual e atrasada

RESUMO Objetivo: comparar os efeitos imediatos do atraso na retroalimentação auditiva na tarefa de leitura oral em escolares com gagueira do desenvolvimento persistente. Métodos: estudo aprovado pelo Comitê de Ética da Instituição (n°0714/2013). Participaram 16 escolares, com idade de 8 a 17 anos, sendo 11 do gênero masculino e 5 do feminino, separados em dois Grupos Experimentais (GE1 e GE2) de 8 participantes cada; o GE1 composto de participantes com gagueira moderada e o GE2 com gagueira grave ou muito grave. Os procedimentos utilizados foram: avaliação audiológica, avaliação da fluência na fala espontânea e avaliação da fluência na leitura oral em duas condições de escuta: com Retroalimentação Auditiva Habitual - RAH e atrasada - RAA. O software Fono Tools junto com o Adaptador Andrea PureAudio USB-AS e microfone auricular Karsect HT-2 foram utilizados para provocar o efeito da RAA e gravar a fala. Resultados: o efeito da retroalimentação auditiva atrasada ocasionou redução das disfluências típicas da gagueira em ambos os grupos, porém a frequência de outras disfluências aumentou no grupo de gagueira moderada e diminuiu no grupo com gagueira grave/muito grave e, desta forma, o total de disfluências apresentou uma diminuição mais significativa no GE2. A diferença foi estatisticamente significante apenas na comparação intergrupos das disfluências típicas da gagueira, na situação de retroalimentação auditiva habitual. Conclusões: o atraso na retroalimentação auditiva não ocasionou efeitos significantes na leitura em ambos os grupos, entretanto há uma tendência do efeito ser considerado positivo para o grupo com gagueira grave/muito grave.

Comparison of audio and audiovisual measures of adult stuttering: Implications for clinical trials

PURPOSE

This study investigated whether measures of percentage syllables stuttered (%SS) and stuttering severity ratings with a 9-point scale differ when made from audiovisual compared with audio-only recordings.

METHOD

Four experienced speech-language pathologists measured %SS and assigned stuttering severity ratings to 10-minute audiovisual and audio-only recordings of 36 adults.

RESULT

There was a mean 18% increase in %SS scores when samples were presented in audiovisual compared with audio-only mode. This result was consistent across both higher and lower %SS scores and was found to be directly attributable to counts of stuttered syllables rather than the total number of syllables. There was no significant difference between stuttering severity ratings made from the two modes.

CONCLUSION

In clinical trials research, when using %SS as the primary outcome measure, audiovisual samples would be preferred as long as clear, good quality, front-on images can be easily captured. Alternatively, stuttering severity ratings may be a more valid measure to use as they correlate well with %SS and values are not influenced by the presentation mode.

Stuttering as a trait or state - an ALE meta-analysis of neuroimaging studies

Stuttering is a speech disorder characterised by repetitions, prolongations and blocks that disrupt the forward movement of speech. An earlier meta-analysis of brain imaging studies of stuttering (Brown et al., 2005) revealed a general trend towards rightward lateralization of brain activations and hyperactivity in the larynx motor cortex bilaterally. The present study sought not only to update that meta-analysis with recent work but to introduce an important distinction not present in the first study, namely the difference between 'trait' and 'state' stuttering. The analysis of trait stuttering compares people who stutter (PWS) with people who do not stutter when behaviour is controlled for, i.e., when speech is fluent in both groups. In contrast, the analysis of state stuttering examines PWS during episodes of stuttered speech compared with episodes of fluent speech. Seventeen studies were analysed using activation likelihood estimation. Trait stuttering was characterised by the well-known rightward shift in lateralization for language and speech areas. State stuttering revealed a more diverse pattern. Abnormal activation of larynx and lip motor cortex was common to the two analyses. State stuttering was associated with overactivation in the right hemisphere larynx and lip motor cortex. Trait stuttering was associated with overactivation of lip motor cortex in the right hemisphere but underactivation of larynx motor cortex in the left hemisphere. These results support a large literature highlighting laryngeal and lip involvement in the symptomatology of stuttering, and disambiguate two possible sources of activation in neuroimaging studies of persistent developmental stuttering.

Systematic studies of modified vocalization: the effect of speech rate on speech production measures during metronome-paced speech in persons who stutter

BACKGROUND

Metronome-paced speech results in the elimination, or substantial reduction, of stuttering moments. The cause of fluency during this fluency-inducing condition is unknown. Several investigations have reported changes in speech pattern characteristics from a control condition to a metronome-paced speech condition, but failure to control speech rate between conditions limits our ability to determine if the changes were necessary for fluency.

AIMS

This study examined the effect of speech rate on several speech production variables during one-syllable-per-beat metronomic speech in order to determine changes that may be important for fluency during this fluency-inducing condition.

METHODS & PROCEDURES

Thirteen persons who stutter (PWS), aged 18-62 years, completed a series of speaking tasks. Several speech production variables were compared between conditions produced at different metronome beat rates, and between a control condition and a metronome-paced speech condition produced at a rate equal to the control condition.

OUTCOMES & RESULTS

Vowel duration, voice onset time, pressure rise time and phonated intervals were significantly impacted by metronome beat rate. Voice onset time and the percentage of short (30-100 ms) phonated intervals significantly decreased from the control condition to the equivalent rate metronome-paced speech condition.

CONCLUSIONS & IMPLICATIONS

A reduction in the percentage of short phonated intervals may be important for fluency during syllable-based metronome-paced speech for PWS. Future studies should continue examining the necessity of this reduction. In addition, speech rate must be controlled in future fluency-inducing condition studies, including neuroimaging investigations, in order for this research to make a substantial contribution to finding the fluency-inducing mechanism of fluency-inducing conditions.

The effect of speech rate on stuttering frequency, phonated intervals, speech effort, and speech naturalness during chorus reading

PURPOSE

This study examined the effect of speech rate on phonated intervals (PIs), in order to test whether a reduction in the frequency of short PIs is an important part of the fluency-inducing mechanism of chorus reading. The influence of speech rate on stuttering frequency, speaker-judged speech effort, and listener-judged naturalness was also examined. An added purpose was to determine if chorus reading could be further refined so as to provide a perceptual guide for gauging the level of physical effort exerted during speech production.

METHODS

A repeated-measures design was used to compare data obtained during control reading conditions and during several chorus reading conditions produced at different speech rates. Participants included 8 persons who stutter (PWS) between the ages of 16 and 32 years.

RESULTS

There were significant reductions in the frequency of short PIs from the habitual reading condition during slower chorus conditions, no change when speech rates were matched between habitual reading and chorus conditions, and an increase in the frequency of short PIs during chorus reading produced at a faster rate than the habitual condition. Speech rate did not have an effect on stuttering frequency during chorus reading. In general, speech effort ratings improved and naturalness ratings worsened as speech rate decreased.

CONCLUSION

These results provide evidence that (a) a reduction in the frequency of short PIs is not necessary for fluency improvement during chorus reading, and (b) speech rate may be altered to provide PWS with a more appropriate reference for how physically effortful normally fluent speech production should be. Future investigations should examine the necessity of changes in the activation of neural regions during chorus reading, the possibility of defining individualized units on a 9-point effort scale, and if there are upper and lower speech rate boundaries for receiving ratings of "highly natural sounding" speech during chorus reading.

LEARNING OUTCOMES

The reader will be able to: (1) describe the effect of changes in speech rate on the frequency of short phonated intervals during chorus reading, (2) describe changes to speaker-judged speech effort as speech rate changes during chorus reading, (3) and describe the effect of changes in speech rate on listener-judged naturalness ratings during chorus reading.