The effect of SpeechEasy on stuttering frequency, speech rate, and speech naturalness

"Lombard Effect" and Voice Changes in Adductor Laryngeal Dystonia: A Pilot Study

OBJECTIVES

The aim was to describe the acoustic, auditory-perceptive, and subjective voice changes under the Lombard effect (LE) in adductor laryngeal dystonia (AdLD) patients.

METHODS

Subjective perception of vocal effort (OMNI Vocal Effort Scale OMNI-VES), Maximum Phonation Time (MPT), and the perceptual severity of dysphonia (GRBAS scale) were assessed in condition of stillness and under LE in 10 AdLD patients and in 10 patients with typical voice. Speakers were asked to produce the sustained vowel /a/ and to read a phonetically balanced text aloud. Using the PRAAT software, the following acoustic parameters were analyzed: Mean Pitch (Hz), Minimum and Maximum Intensity (dB), the Fraction of Locally Unvoiced Frames, the Number of Voice Breaks, the Degree of Voice Breaks (%), the Cepstral Peak Prominence-Smoothed (CPPS) (dB).

RESULTS

Under LE, the AdLD group showed a decrease of both G and S parameters of GRBAS and subjective effort, mean MPT increased significantly; in the controls there were no significant changes. In both groups under LE, pitch and intensity of the sustained vowel /a/ significantly increased consistently with LE. In the AdLD group the mean gain of OMNI-VES score and the mean gain of each parameter of the speech analysis were significantly greater than the controls' ones.

CONCLUSION

Auditory feedback deprivation obtained under LE improves subjective, perceptual-auditory, and acoustics parameters of AdLD patients. These findings encourage further research to provide new knowledge into the role of the auditory system in the pathogenesis of AdLD and to develop new therapeutic strategies.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:3754-3760, 2024.

Deficit or Difference? Effects of Altered Auditory Feedback on Speech Fluency and Kinematic Variability in Adults Who Stutter

Purpose The purpose of this study was to test whether adults who stutter (AWS) display a different range of sensitivity to delayed auditory feedback (DAF). Two experiments were conducted to assess the fluency of AWS under long-latency DAF and to test the effect of short-latency DAF on speech kinematic variability in AWS. Method In Experiment 1, 15 AWS performed a conversational speaking task under nonaltered auditory feedback and 250-ms DAF. The rates of stuttering-like disfluencies, other disfluencies, and speech errors and articulation rate were compared. In Experiment 2, 13 AWS and 15 adults who do not stutter (AWNS) read three utterances under four auditory feedback conditions: nonaltered auditory feedback, amplified auditory feedback, 25-ms DAF, and 50-ms DAF. Across-utterance kinematic variability (spatiotemporal index) and within-utterance variability (percent determinism and stability) were compared between groups. Results In Experiment 1, under 250-ms DAF, the rate of stuttering-like disfluencies and speech errors increased significantly, while articulation rate decreased significantly in AWS. In Experiment 2, AWS exhibited higher kinematic variability than AWNS across the feedback conditions. Under 25-ms DAF, the spatiotemporal index of AWS decreased significantly compared to the other feedback conditions. AWS showed lower overall percent determinism than AWNS, but their percent determinism increased under 50-ms DAF to approximate that of AWNS. Conclusions Auditory feedback manipulations can alter speech fluency and kinematic variability in AWS. Longer latency auditory feedback delays induce speech disruptions, while subtle auditory feedback manipulations potentially benefit speech motor control. Both AWS and AWNS are susceptible to auditory feedback during speech production, but AWS appear to exhibit a distinct continuum of sensitivity.

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.

Auditory Feedback Control of Vocal Pitch in Spasmodic Dysphonia

OBJECTIVES/HYPOTHESIS

Hearing plays an important role in the maintenance of vocal control in normal individuals. In patients with spasmodic dysphonia (SD), however, the ability to maintain sustained control of phonation is impaired. The origins of SD are unknown, and it is unclear whether auditory feedback-dependent vocal control is compromised in these patients.

STUDY DESIGN

Prospective case-control study.

METHODS

We tested 15 SD patients and 11 age-matched controls. Voice recordings were performed while subjects repeated the vowel /e/ and auditory feedback of their vocal sounds was altered in real-time to introduce a pitch-shift (±2 semitones), presented back to subjects using headphones. Recordings were analyzed to determine voice changes following the pitch-shifted feedback. Results were further compared with patient demographics and subjective measures of dysphonia, including the Voice Handicap Index (VHI).

RESULTS

Despite considerable pitch variability and vocal breaks, SD patients exhibited significantly higher average vocal pitch compensation than control subjects. SD patients also exhibited greater variability than controls. However, there were no significant correlations between vocal compensation and patient demographics, although there was a significant inverse correlation with VHI.

CONCLUSIONS

In this pilot study, patients with SD exhibited increased sensitivity to altered auditory feedback during sustained phonation. These results are consistent with recent theories of SD as a disorder of sensory-motor feedback processing, and suggest possible avenues for future investigation.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:2070-2075, 2021.

Coarticulatory Aspects of the Fluent Speech of French and Italian People Who Stutter Under Altered Auditory Feedback

A number of studies have shown that phonetic peculiarities, especially at the coarticulation level, exist in the disfluent as well as in the perceptively fluent speech of people who stutter (PWS). However, results from fluent speech are very disparate and not easily interpretable. Are the coarticulatory features observed in fluent speech of PWS a manifestation of the disorder, or rather a compensation for the disorder itself? The purpose of the present study is to investigate the coarticulatory behavior in the fluent speech of PWS in the attempt to answer the question on its symptomatic or adaptive nature. In order to achieve this, we have studied the speech of 21 adult PWS (10 French and 11 Italian) compared to that of 20 fluent adults (10 French and 10 Italian). The participants had to repeat simple CV syllables in short carrier sentences, where C = /b, d, g/ and V = /a, i, u/. Crucially, this repetition task was performed in order to compare fluent speech coarticulation of PWS to that of PWNS, and to compare the coarticulation of PWS under a condition with normal auditory feedback (NAF) and under a fluency-enhancing condition due to an altered auditory feedback (AAF). This is the first study, to our knowledge, to investigate the coarticulation behavior under AAF. The degree of coarticulation was measured by means of the Locus Equations (LE). The coarticulation degree observed in fluent PWS speech is lower than that of the PWNS, and, more importantly, in AAF condition, PWS coarticulation appears even weaker than in the NAF condition. The results allow to interpret the lower degree of coarticulation found in fluent speech of PWS under NAF condition as a compensation for the disorder, based on the fact that PWS’s coarticulation is weakening in fluency-enhancing conditions, further away from the degree of coarticulation observed in PWNS. Since a lower degree of coarticulation is associated to a greater separation between the places of articulation of the consonant and the vowel, these results are compatible with the hypothesis that larger articulatory movements could be responsible for the stabilization of the PWS speech motor system, increasing the kinesthetic feedback from the effector system. This interpretation shares with a number of relatively recent proposal the idea that stuttering derives from an impaired feedforward (open-loop) control system, which makes PWS rely more heavily on a feedback-based (closed loop) motor control strategy.

Acoustically controlled auditory training in children with speech disfluency: a case report

ABSTRACT The purpose of this study was to verify the effect of the acoustically controlled auditory training on the speech fluency of children diagnosed with developmental stuttering. Two patients were submitted to speech fluency evaluation, basic audiological assessment, and central auditory processing assessment, before and after the intervention with the digital platform. Two male individuals (P1 and P2) participated in the research. They were respectively 8 and 9 years old, both were right-handed, native Brazilian Portuguese speakers, diagnosed with developmental stuttering, P1 presenting a moderate, and P2, a mild-to-moderate degree. There was an improvement in some auditory skills. However, there was no improvement in the speech fluency pattern in neither of the cases studied.

Immediate effect of delayed auditory feedback on stuttering-like disfluencies

ABSTRACT Objective: to describe the immediate effects of delayed auditory feedback on stuttering-like disfluencies in people who stutter. Methods: a cross-sectional and experimental study. The effect of delayed auditory feedback was analyzed in thirty individuals, from eight to 46 years old, diagnosed with persistent developmental stuttering. Participants should present at least 3% of stuttering-like disfluencies and mild stuttering according to the Stuttering Severity Instrument. The following procedures were used: audiological evaluation, fluency evaluation in two listening situations - with Non-altered and delayed auditory feedback - and the Stuttering Severity Instrument. The Fono Tools software was used to cause the delay effect. Data analysis was performed using pertinent statistical tests. Results: there was no decrease in most stuttering-like disfluencies. There was a statistically significant reduction in word repetition and flow of syllables per minute. Conclusion: the delay in auditory feedback caused, as an immediate effect, the reduction of word repetition and speech rate, in syllables per minute.

Non-pharmacological treatments for stuttering in children and adults: a systematic review and evaluation of clinical effectiveness, and exploration of barriers to successful outcomes

BACKGROUND

Despite many years of research, there is no certainty regarding the cause of stuttering. Although numerous interventions have been developed, a broad-based systematic review across all forms of intervention for adults and children was needed including views and perceptions of people who stutter.

OBJECTIVE

The aims of the study were to report the clinical effectiveness of interventions for people who stutter (or clutter), to examine evidence regarding the views of people who stutter and the views of professionals regarding interventions.

DATA SOURCES

A systematic review of quantitative and qualitative literature was carried out between August 2013 and April 2014. The following electronic databases were searched: (1) MEDLINE, (2) EMBASE, (3) The Cochrane Library (including The Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Database of Abstracts of Reviews of Effects, Health Technology Assessment Database and NHS Economic Evaluations Database), (4) PsycINFO, (5) Science Citation Index, (6) Social Science Citation Index, (7) Cumulative Index to Nursing and Allied Health Literature, (8) ASSIA, (9) Linguistics and Language Behavior Abstracts, (10) Sociological Abstracts and (11) the EPPI Centre. Reference lists of included papers and other reviews were screened and also key journals in the subject area were hand-searched.

REVIEW METHODS

The searches aimed to identify (1) evidence of clinical effectiveness in populations of pre-school children, school-aged children, adolescents and adults, and (2) data relating to perceptions of barriers and facilitators to intervention clinical effectiveness among staff and people who stutter. A metasynthesis of the two linked elements via development of a conceptual model was also carried out to provide further interpretation of the review findings.

RESULTS

A systematic search of the literature identified a large number of potentially relevant studies. Of these, 111 studies examining the clinical effectiveness of interventions, 25 qualitative papers and one mixed-methods paper met the criteria for inclusion in this review. Review of the effectiveness literature indicated evidence of positive outcomes across all types of interventions. Virtually all evidence we identified reported at least some positive effect for some participants. However, there was evidence of considerable individual variation in outcome for study participants. The qualitative literature highlighted the need for programmes to be tailored to individual need with variation at the levels of the intervention, the individual and interpersonal/social elements. Metasynthesis of the data highlighted the complexity of elements that need to be considered in evaluation of long-term impacts following stuttering interventions.

LIMITATIONS

Around two-thirds of the studies were considered to be at higher risk of bias. The heterogeneous nature and variability in outcomes meant that we were unable to complete a meta-analysis.

CONCLUSIONS

Although much of the evidence we identified was from studies at risk of bias, it is suggested that most available interventions for stuttering may be of benefit to at least some people who stutter. There is a requirement for greater clarity regarding what the core outcomes following stuttering intervention should be and also enhanced understanding of the process whereby interventions effect change. Further analysis of those for whom interventions have not produced a significant benefit may provide additional insights into the complex intervention-outcomes pathway.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013004861.

The state of the art in non-pharmacological interventions for developmental stuttering. Part 1: a systematic review of effectiveness

BACKGROUND

The growing range of available treatment options for people who stutter presents a challenge for clinicians, service managers and commissioners, who need to have access to the best available treatment evidence to guide them in providing the most appropriate interventions. While a number of reviews of interventions for specific populations or a specific type of intervention have been carried out, a broad-based systematic review across all forms of intervention for adults and children was needed to provide evidence to underpin future guidelines, inform the implementation of effective treatments and identify future research priorities.

AIMS

To identify and synthesize the published research evidence on the clinical effectiveness of the broad range of non-pharmacological interventions for the management of developmental stuttering.

METHODS & PROCEDURES

A systematic review of the literature reporting interventions for developmental stuttering was carried out between August 2013 and April 2014. Searches were not limited by language or location, but were restricted by date to studies published from 1990 onwards. Methods for the identification of relevant studies included electronic database searching, reference list checking, citation searching and hand searching of key journals. Appraisal of study quality was performed using a tool based on established criteria for considering risk of bias. Due to heterogeneity in intervention content and outcomes, a narrative synthesis was completed.

MAIN CONTRIBUTION

The review included all available types of intervention and found that most may be of benefit to at least some people who stutter. There was evidence, however, of considerable individual variation in response to these interventions. The review indicated that effects could be maintained following all types of interventions (although this was weakest with regard to feedback and technology interventions).

CONCLUSIONS

This review highlights a need for greater consensus with regard to the key outcomes used to evaluate stuttering interventions, and also a need for enhanced understanding of the process whereby interventions effect change. Further analysis of the variation in effectiveness for different individuals or groups is needed in order to identify who may benefit most from which intervention.

O efeito do feedback auditivo atrasado na gagueira

Objetivo Verificar o efeito do feedback auditivo atrasado (delay auditory feedback) e da retroalimentação com a frequência alterada (frequency altered feedback) em indivíduos que manifestam gagueira. Métodos Foram selecionados 16 indivíduos adultos com diagnóstico de gagueira, de ambos os gêneros, faixa etária entre 17 e 49 anos e com, no mínimo, 8 anos de escolaridade. Os indivíduos foram distribuídos em dois grupos, sendo um grupo (G1) formado por oito indivíduos gagos submetidos à terapia de fala com o uso do aparelho SpeechEasy® e o outro (G2), formado por oito indivíduos gagos submetidos à terapia sem o uso do aparelho. Todos os indivíduos passaram por avaliação fonoaudiológica convencional, avaliação específica da fluência da fala, avaliação audiológica básica e treinamento de fala com ou sem o uso do aparelho. Os dados obtidos foram submetidos à análise estatística pertinente. Resultados Nos grupos G1 e G2 houve diminuição significativa do grau de gagueira e das disfluências atípicas na avaliação final, quando comparada à inicial. Conclusão Houve melhora do grau da gagueira com o treinamento de fala em ambos os grupos, com tendência do G1, que utilizou o dispositivoSpeechEasy®,para apresentar maior redução no índice de disfluências e maior ganho nas taxas de velocidade articulatória e de produção de informação.

Impacto do uso do SpeechEasy® nos parâmetros acústicos e motores da fala de indivíduos com gagueira

Objetivo Investigar variações nas habilidades motoras da fala em adultos com e sem gagueira, utilizando o dispositivo de alteração do feedback auditivo SpeechEasy®. Métodos Participaram 20 adultos, dez com gagueira (nove do gênero masculino e um do feminino – média 30,9 anos) e dez controles fluentes (nove do gênero masculino e um do feminino – média 25,2 anos). O estudo comparou o desempenho dos participantes em quatro tarefas: fala espontânea, diadococinesia alternada, diadococinesia sequencial e emissão de frase alvo, com e sem o dispositivo. Os aspectos analisados acusticamente foram: (1) tarefas de diadococinesia: duração das sílabas, período médio entre as sílabas, pico de intensidade e taxa de diadococinesia; (2) tarefa de emissão da frase alvo: tempo de reação, duração do voice onset time, duração total da emissão, frequência fundamental e intensidade. Resultados Tanto na comparação intragrupos quanto intergrupos, apenas a tarefa de fala espontânea apresentou diferenças significativas. Nesta tarefa, o uso do SpeechEasy® resultou em melhora significativa da fluência de fala, medida pela porcentagem de sílabas gaguejadas, para o grupo com gagueira. Para o grupo fluente, o dispositivo produziu o efeito oposto (aumento significativo na frequência de rupturas gagas com o dispositivo). Os resultados encontrados quanto aos aspectos acústicos das tarefas de diadococinesia e emissão da frase alvo não indicaram diferença significativa nas comparações intragrupos e intergrupos. Conclusão Os resultados indicaram que o uso do SpeechEasy® melhorou a fluência dos participantes com gagueira, sem parecer interferir na naturalidade de fala.

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.

The Role of Rhythm in Speech and Language Rehabilitation: The SEP Hypothesis

For thousands of years, human beings have engaged in rhythmic activities such as drumming, dancing, and singing. Rhythm can be a powerful medium to stimulate communication and social interactions, due to the strong sensorimotor coupling. For example, the mere presence of an underlying beat or pulse can result in spontaneous motor responses such as hand clapping, foot stepping, and rhythmic vocalizations. Examining the relationship between rhythm and speech is fundamental not only to our understanding of the origins of human communication but also in the treatment of neurological disorders. In this paper, we explore whether rhythm has therapeutic potential for promoting recovery from speech and language dysfunctions. Although clinical studies are limited to date, existing experimental evidence demonstrates rich rhythmic organization in both music and language, as well as overlapping brain networks that are crucial in the design of rehabilitation approaches. Here, we propose the “SEP” hypothesis, which postulates that (1) “sound envelope processing” and (2) “synchronization and entrainment to pulse” may help stimulate brain networks that underlie human communication. Ultimately, we hope that the SEP hypothesis will provide a useful framework for facilitating rhythm-based research in various patient populations.

Absolute and relative reliability of percentage of syllables stuttered and severity rating scales

PURPOSE

Percentage of syllables stuttered (%SS) and severity rating (SR) scales are measures in common use to quantify stuttering severity and its changes during basic and clinical research conditions. However, their reliability has not been assessed with indices measuring both relative and absolute reliability. This study was designed to provide such information. Relative reliability deals with the rank order of participants in a sample, whereas absolute reliability measures the closeness of scores to one other and to a hypothetical true score.

METHOD

Eighty-seven adult participants who stutter received a 10-min unscheduled telephone call. Three experienced judges measured %SS and also used a 9-point SR scale to measure stuttering severity from recordings of the telephone calls.

RESULTS

Relative intrajudge and interjudge reliability were satisfactory for both scales. However, absolute intrajudge and interjudge reliability were not satisfactory. Results showed that paired-judge SR and %SS procedures improved absolute reliability compared with single-judge measures. Additionally, the paired-judge procedure improved relative reliability from high to very high levels.

CONCLUSION

Measurement of group changes of stuttering severity can be done in research contexts using either %SS or SR. However, for detecting changes within individuals using such measures, a paired-judge procedure is a more reliable method.

Stuttering inhibition via altered auditory feedback during scripted telephone conversations

BACKGROUND

Overt stuttering is inhibited by approximately 80% when people who stutter read aloud as they hear an altered form of their speech feedback to them. However, levels of stuttering inhibition vary from 60% to 100% depending on speaking situation and signal presentation. For example, binaural presentations of delayed auditory feedback (DAF) and frequency-altered feedback (FAF) have been shown to reduce stuttering by approximately 57% during scripted telephone conversations.

AIMS

To examine stuttering frequency under monaural auditory feedback with one combination of DAF with FAF (COMBO-2) and two combinations of DAF with FAF (COMBO-4) during scripted telephone conversations.

METHODS & PROCEDURES

Nine adult participants who stutter called 15 local businesses during scripted telephone conversations; each condition consisted of five randomized telephone calls. Conditions consisted of (1) baseline (i.e. non-altered feedback), (2) COMBO-2 (i.e. 50-ms delay with a half octave spectral shift up), and (3) COMBO-4 (i.e. 200-ms delay and a half octave spectral shift down in addition to the COMBO-2). Participants wore a supra-aural headset with a dynamic condenser microphone while holding a receiver to their contralateral ear when making telephone calls.

OUTCOMES & RESULTS

Stuttering was significantly reduced during both altered auditory feedback (AAF) conditions by approximately 65%. Furthermore, a greater reduction in stuttering was revealed during the COMBO with four effects (74%) as compared with the COMBO with two effects (63%).

CONCLUSIONS & IMPLICATIONS

Results from the current study support prior research reporting decreased stuttering under AAF during scripted telephone conversations. Findings that stuttering was significantly reduced to a greater extent under the COMBO with four effects condition suggest that second signals reduce stuttering along a continuum. Additionally, findings support prior research results of decreased stuttering frequency under AAF during hierarchically difficult speaking situations. Clinical application of these findings may be that people who stutter can use specific software or smartphone applications that produce second speech signals to inhibit stuttering frequency effectively during telephone conversations.

The SpeechEasy device in stuttering and nonstuttering adults: fluency effects while speaking and reading

The SpeechEasy is an electronic device designed to alleviate stuttering by manipulating auditory feedback via time delays and frequency shifts. Device settings (control, default, custom), ear-placement (left, right), speaking task, and cognitive variables were examined in people who stutter (PWS) (n=14) compared to controls (n=10). Among the PWS there was a significantly greater reduction in stuttering (compared to baseline) with custom device settings compared to the non-altered feedback (control) condition. Stuttering was reduced the most during reading, followed by narrative and conversation. For the conversation task, stuttering was reduced more when the device was worn in the left ear. Those individuals with a more severe stuttering rate at baseline had a greater benefit from the use of the device compared to individuals with less severe stuttering. Our results support the view that overt stuttering is associated with defective speech-language monitoring that can be influenced by manipulating auditory feedback.

Influence of analogy instruction for pitch variation on perceptual ratings of other speech parameters

PURPOSE

Analogy is the similarity of different concepts on which a comparison can be based. Recently, an analogy of "waves at sea" was shown to be effective in modulating fundamental frequency (F0) variation. Perceptions of intonation were not examined, as the primary aim of the work was to determine whether analogy instruction had a negative impact on other parameters of the speech signal compared with explicit instruction. The purpose of this study was (a) to determine whether changes in the standard deviation of F0, acoustically, resulted in similar changes in the perception of pitch variability and (b) to determine the perceptual influence of analogy vs. explicit instructions on speech naturalness, loudness, and rate.

METHOD

Ten speech-language pathologists were asked to listen to and rate pitch variation, speech naturalness, loudness, and rate for 74 Cantonese speech samples using a visual analogue scale, which allowed raters to indicate their subjective perceptions of each parameter.

RESULTS

It is revealed that listeners perceived pitch variation to be greater and speech to be more natural in analogy-instructed, rather than explicitly instructed, speech. No differences were perceived for ratings of speech loudness or speech rate.

CONCLUSION

It is concluded that analogy instruction has a less negative impact on the naturalness of speech than explicit instruction and may provide a better method by which to manipulate desired pitch variation.

Immediate effects of AAF devices on the characteristics of stuttering: a clinical analysis

The present study investigated the immediate effects of altered auditory feedback (AAF) and one Inactive Condition (AAF parameters set to 0) on clinical attributes of stuttering during scripted and spontaneous speech. Two commercially available, portable AAF devices were used to create the combined delayed auditory feedback (DAF) and frequency altered feedback (FAF) effects. Thirty adults, who stutter, aged 18-68 years (M=36.5; SD=15.2), participated in this investigation. Each subject produced four sets of 5-min of oral reading, three sets of 5-min monologs as well as 10-min dialogs. These speech samples were analyzed to detect changes in descriptive features of stuttering (frequency, duration, speech/articulatory rate, core behaviors) across the various speech samples and within two SSI-4 (Riley, 2009) based severity ratings. A statistically significant difference was found in the frequency of stuttered syllables (%SS) during both Active Device conditions (p=.000) for all speech samples. The most sizable reductions in %SS occurred within scripted speech. In the analysis of stuttering type, it was found that blocks were reduced significantly (Device A: p=.017; Device B: p=.049). To evaluate the impact on severe and mild stuttering, participants were grouped into two SSI-4 based categories; mild and moderate-severe. During the Inactive Condition those participants within the moderate-severe group (p=.024) showed a statistically significant reduction in overall disfluencies. This result indicates, that active AAF parameters alone may not be the sole cause of a fluency-enhancement when using a technical speech aid.

EDUCATIONAL OBJECTIVES

The reader will learn and be able to describe: (1) currently available scientific evidence on the use of altered auditory feedback (AAF) during scripted and spontaneous speech, (2) which characteristics of stuttering are impacted by an AAF device (frequency, duration, core behaviors, speech & articulatory rate, stuttering severity), (3) the effects of an Inactive Condition on people who stutter (PWS) falling into two severity groups, and (4) how the examined participants perceived the use of AAF devices.

Análise sistemática da efetividade do uso da alteração do feedback auditivo para a redução da gagueira

OBJETIVO: Realizar uma revisão sistemática de pesquisas relacionadas aos efeitos da alteração do feedback auditivo sobre a fluência da fala em pessoas com gagueira. ESTRATÉGIA DE PESQUISA: Foram seguidos os preceitos do Cochrane Handbook: formulação da pergunta inicial (tema a ser pesquisado), localização e seleção dos estudos (base de dados PubMed) e compatibilização entre os pesquisadores (visando minimizar possíveis perdas de citações). CRITÉRIOS DE SELEÇÃO: Foram excluídas: citações em línguas que não fossem o Inglês, citações que não permitiram o acesso ao texto completo, citações repetidas por sobreposição das palavras-chave utilizadas, pesquisas realizadas exclusivamente com indivíduos fluentes; estudos de caso; revisões de literatura; cartas ao editor e textos que não se relacionavam diretamente ao tema. Desta forma, foram analisados os textos que efetivamente se relacionavam às pesquisas de tratamento com delayed auditory feedback (DAF)e o frequency-altered feedback (FAF). ANÁLISE DOS DADOS: Os dados foram analisados quanto aos indicadores da pesquisa e quanto aos marcadores de qualidade dos estudos. RESULTADOS: Os resultados indicaram que o uso dos dispositivos de alteração do feedback auditivo na redução do número de eventos de gagueira ainda não tem suporte robusto em sua aplicabilidade. A variabilidade de método não permite uma resposta ou uma tendência de resposta que possa ser considerada consistente sobre a eficácia do dispositivo. CONCLUSÃO: Embora as limitações apontadas nos estudos impeçam generalizações sobre a eficácia do uso do dispositivo para a redução da gagueira, essas mesmas limitações são recursos importantes para o planejamento de pesquisas futuras.

An experimental investigation of the effect of altered auditory feedback on the conversational speech of adults who stutter

PURPOSE

To investigate the impact on percentage of syllables stuttered of various durations of delayed auditory feedback (DAF), levels of frequency-altered feedback (FAF), and masking auditory feedback (MAF) during conversational speech.

METHOD

Eleven adults who stuttered produced 10-min conversational speech samples during a control condition and under 4 different combinations of DAF, FAF, and MAF. Participants also read aloud in a control condition with DAF and FAF.

RESULTS

A statistically significant difference was found between the NAF conversation condition and the 4 combined altered auditory feedback (AAF) conditions. No statistically significant differences in percentage of syllables stuttered were found in conversation or reading between the control conditions and the FAF/DAF or MAF conditions. The analysis of individual participants' data showed highly individual responsiveness to different conditions.

CONCLUSIONS

Participants' varying responses to differing AAF settings likely accounted for the failure to find group differences between conditions. These results suggest that studies that use standard DAF and FAF settings for all participants are likely to underestimate any AAF effect. It is not yet possible to predict who will benefit from AAF devices in everyday situations and the extent of those benefits.

Overreliance on auditory feedback may lead to sound/syllable repetitions: simulations of stuttering and fluency-inducing conditions with a neural model of speech production

This paper investigates the hypothesis that stuttering may result in part from impaired readout of feedforward control of speech, which forces persons who stutter (PWS) to produce speech with a motor strategy that is weighted too much toward auditory feedback control. Over-reliance on feedback control leads to production errors which if they grow large enough, can cause the motor system to "reset" and repeat the current syllable. This hypothesis is investigated using computer simulations of a "neurally impaired" version of the DIVA model, a neural network model of speech acquisition and production. The model's outputs are compared to published acoustic data from PWS' fluent speech, and to combined acoustic and articulatory movement data collected from the dysfluent speech of one PWS. The simulations mimic the errors observed in the PWS subject's speech, as well as the repairs of these errors. Additional simulations were able to account for enhancements of fluency gained by slowed/prolonged speech and masking noise. Together these results support the hypothesis that many dysfluencies in stuttering are due to a bias away from feedforward control and toward feedback control.

EDUCATIONAL OBJECTIVES

The reader will be able to (a) describe the contribution of auditory feedback control and feedforward control to normal and stuttered speech production, (b) summarize the neural modeling approach to speech production and its application to stuttering, and (c) explain how the DIVA model accounts for enhancements of fluency gained by slowed/prolonged speech and masking noise.

Refutation of a therapeutic alternative? A reply to Pollard, Ellis, Finan, and Ramig (2009)

PURPOSE

To challenge the findings of Pollard, Ellis, Finan, and Ramig (2009), who examined 11 participants using the SpeechEasy, an in-the-ear device that employs altered auditory feedback to reduce stuttering, in a 6-month "clinical trial." Pollard et al. failed to demonstrate a significant treatment effect on stuttering frequency, yet found positive subjective self-report data across four months of use. The authors concluded that the device was not therapeutically useful and further testing is unwarranted.

RESULTS

We dispute Pollard et al. on the following grounds: Their operational definition of stuttering is confounded as it does not adequately distinguish true stuttering from "normally" disfluent speech or from volitionally produced initiating gestures taught to be used as part of the treatment protocol, nor is it the definition used in their pre- and posttreatment stuttering assessment instrument; they failed to maintain participant adherence to the treatment protocol of device usage; they utilized an inadequate question-asking task; and their conclusion of no significant treatment effect that is drawn from their inferential statistical analyses of group data.

CONCLUSIONS

In light of problematic objective measurements, reported positive subjective findings, a robust corpus of contradictory data, and the need for alternative stuttering treatments, we argue that the SpeechEasy merits further investigation.

Disfluencies in non-stuttering adults across sample lengths and topics

Data on disfluencies in the speech of non-stuttering adults are relevant to several aspects of the assessment and treatment of adults who stutter. Currently, very few sources provide relevant data. In the existing literature on normally fluent speakers, there is no consistency in sample length or topic or in which types of disfluency are counted. Many studies report incomplete data, making it difficult to compare new results to previous ones. The purpose of this study was to assess the effect of sample length and topic on fluency levels in the speech of non-stuttering adult men. Monologues produced by 25 English-speaking men with no reported communication disorder were analyzed for the presence of disfluencies. The group means for total disfluencies were between 6 and 8 per 100 syllables for all samples. A within-subjects Length (3) by Topic (3) ANOVA found a significant interaction (Length by Topic), however, the clinical importance of this result is minimal. The mean number of within-word disfluencies (also called stuttering-like disfluencies or SLDs) was below 1.5 per 100 syllables for all samples, although there was some variation across individual speakers. The data presented will be useful to clinicians and to researchers interested in disfluencies in spontaneous speech.

LEARNING OUTCOMES

Readers will be able to (1) identify several methodological problems in studies of disfluency including counting methods and descriptions of participants; (2) identify the range of within-word disfluencies (also called SLDs) and other disfluencies in this study and other similar ones; (3) know whether topic/type of speech or sample length is more likely to affect disfluency levels in non-stuttering adults.

Effects of the SpeechEasy on objective and perceived aspects of stuttering: a 6-month, phase I clinical trial in naturalistic environments

PURPOSE

Effects of the SpeechEasy when used under extraclinical conditions over several months were investigated. Primary purposes were to help establish Phase I level information about the therapeutic utility of the SpeechEasy and to compare those results with previous findings obtained in laboratory and clinical settings.

METHOD

Eleven adults who stutter participated. A nonrandomized ABA group design was utilized. Speech samples were collected every 2 weeks in extraclinical environments. Qualitative data were collected through weekly written logs and an exit questionnaire.

RESULTS

Group analyses revealed a statistically significant effect of the SpeechEasy immediately postfitting but no treatment effect across 4 months' time. Individual responses varied greatly with regard to stuttering frequency and subjective impressions. Relatively more stuttering reduction occurred during oral reading than during formulated speech.

CONCLUSIONS

Based on this protocol, Phase II trials are not indicated. However, positive individual responses and self-reports suggest some clinical utility for the SpeechEasy. The use of more challenging sampling procedures strengthened external validity and captured more modest altered auditory feedback effects compared with those previously reported in laboratory settings. Device use coincided more so with positive subjective impressions than with measurable fluency improvement, highlighting challenges facing clinicians when implementing principles of evidence-based practice, including client-based preferences.

Effects of altered auditory feedback (AAF) on stuttering frequency during monologue speech production

The present study investigated the immediate effects of eight altered auditory feedback (AAF) parameters on stuttering frequency during monologue speech production on two occasions. One of the modern commercially available portable anti-stuttering devices, "The Pocket Speech Lab" (Casa Futura Technologies) was used in the study to produce the auditory feedback alterations. Six types of combined delayed auditory feedback (DAF) and frequency shifted auditory feedback (FAF) and two types of DAF alone were tested for eight participants aged 16-55 years, with stuttering severity ranging from mild to severe. The present study found that AAF is an effective means to reduce stuttering frequency during monologue speech production. All eight AAF experimental conditions reduced stuttering frequency, however, there was substantial variability in the stuttering reduction effect across experimental conditions and across participants. There was also instability in stuttering reduction across the two testing sessions. On average, a 75 ms time delay on its own and a combination of the 75 ms time delay and a half octave downward frequency shift were found to be more effective than other combinations of AAF parameters that were investigated.

EDUCATIONAL OBJECTIVES

After reading this paper, the reader should be able to (1) summarize the research investigating the effect of altered auditory feedback on stuttering frequency during monologue speech production; (2) describe the stuttering reduction effect of the eight parameters of AAF tested during monologue speech production; and (3) discuss the possible clinical implications of the use of AAF for stuttering treatment.