Mirror neurons as a model for the science and treatment of stuttering.

Persistent developmental stuttering is generally considered a speech disorder and affects ∼1% of the global population. While mainstream treatments continue to rely on unreliable behavioral speech motor targets, an emerging research perspective utilizes the mirror neuron system hypothesis as a neural substrate in the science and treatment of stuttering. The purpose of this exploratory study is to test the viability of the mirror neuron system hypothesis in the fluency enhancement of those who stutter. Participants were asked to speak while they were producing self-generated manual gestures, producing and visually perceiving self-generated manual gestures, and visually perceiving manual gestures, relative to a nonmanual gesture control speaking condition. Data reveal that all experimental speaking conditions enhanced fluent speech in all research participants, and the simultaneous perception and production of manual gesturing trended toward greater efficacious fluency enhancement. Coupled with existing research, we interpret these data as suggestive of fluency enhancement through subcortical involvement within multiple levels of an action understanding mirror neuron network. In addition, incidental findings report that stuttering moments were observed to simultaneously occur both orally and manually. Consequently, these data suggest that stuttering behaviors are compensatory, distal manifestations over multiple expressive modalities to an underlying centralized genetic neural substrate of the disorder.

Novel tactile feedback to reduce overt stuttering.

Stuttering is generally considered to be a speech disorder that affects ∼1% of the global population. Various forms of speech feedback have been shown to reduce overt stuttered speaking, and in particular, second speech signal through speech feedback has drastically reduced utterances of stuttered speech in adults with persistent stuttering. This study reports data for increased overt fluency of speech in an adult stuttering population, whereby the vocalization of the speaker is captured by a microphone or an accelerometer, signal processed, and returned as mechanical tactile speech feedback to the speaker's skin. A repeated measures analysis of variance was used to show that both the microphone and the accelerometer speaking conditions were significantly more fluent than a control (no feedback) condition, with the microphone-driven tactile feedback reducing instances of stuttering by 71% and the accelerometer-driven tactile feedback reducing instances of stuttering by 80%. It is apparent that self-generated tactile feedback can be used to enhance fluency significantly in those who stutter.

Speech rate treatments for individuals with dysarthria: a tutorial.

Research confirms the long-standing clinical observation that patients with dysarthria exhibit variability in speech rate. Thus, modifying speech rate has been documented as one of the best treatment options for these patients. In this tutorial, several published rate control interventions for dysarthric speakers are presented. Studies discussed utilized various interventions, including pacing boards, alphabet board supplementation, visual and auditory feedback, cueing and pacing strategies, and delayed auditory feedback. Interventions discussed represent a hierarchy from "rigid" strategies, which impose maximal rate control, to techniques allowing for greater speech naturalness and independent rate control. All procedures are examined with respect to effectiveness in reducing rate, effect on intelligibility and prosody, training requirements, specific alterations made to speech rate, and other relevant aspects.

Effects of digital vibrotactile speech feedback on overt stuttering frequency.

Fluency-enhancing speech feedback, originating from internally or externally generated sources via auditory or visual sensory modalities is not restricted to a specific sensory modality or signal origination. Research suggests that externally generated digital vibrotactile speech feedback serves as an effective fluency enhancer. The present purpose was to test the fluency-enhancing effects of self-generated digital vibrotactile speech feedback on stuttering frequency. Adults who stutter read passages aloud over the telephone, both with and without digital vibrotactile speech feedback. Digital vibrotactile speech feedback was operationally defined as feeling the vibrations of the thyroid cartilage with the thumb and index finger while speaking. Analysis indicated that self-generated digital vibrotactile speech feedback reduced overt stuttering frequency by an average of 72%. As the specific neural mechanisms associated with stuttering and fluency enhancement from tactile speech feedback remain unknown, theoretical implications and clinical applications were discussed.

The effects of self-generated synchronous and asynchronous visual speech feedback on overt stuttering frequency.

PURPOSE: Relatively recent research documents that visual choral speech, which represents an externally generated form of synchronous visual speech feedback, significantly enhanced fluency in those who stutter. As a consequence, it was hypothesized that self-generated synchronous and asynchronous visual speech feedback would likewise enhance fluency. Therefore, the purpose of this study was to investigate the effects of self-generated visual feedback (i.e., synchronous speech feedback with a mirror and asynchronous speech feedback via delayed visual feedback) on overt stuttering frequency in those who stutter. METHOD: Eight people who stutter (4 males, 4 females), ranging from 18 to 42 years of age participated in this study. Due to the nature of visual speech feedback, the speaking task required that participants recite memorized phrases in control and experimental speaking conditions so that visual attention could be focused on the speech feedback, rather than a written passage. During experimental conditions, participants recited memorized phrases while simultaneously focusing on the movement of their lips, mouth, and jaw within their own synchronous (i.e., mirror) and asynchronous (i.e., delayed video signal) visual speech feedback. RESULTS: Results indicated that the self-generated visual feedback speaking conditions significantly decreased stuttering frequency (Greenhouse-Geisser p=.000); post hoc orthogonal comparisons revealed no significant differences in stuttering frequency reduction between the synchronous and asynchronous visual feedback speaking conditions (p=.2554). CONCLUSIONS: These data suggest that synchronous and asynchronous self-generated visual speech feedback is associated with significant reductions in overt stuttering frequency. Study results were discussed relative to existing theoretical models of fluency-enhancement via speech feedback, such as the engagement of mirror neuron networks, the EXPLAN model, and the Dual Premotor System Hypothesis. Further research in the area of self-generated visual speech feedback, as well as theoretical constructs accounting for how exposure to a multi-sensory speech feedback enhances fluency, is warranted. LEARNING OUTCOMES: : Readers will be able to (1) discuss the multi-sensory nature of fluency-enhancing speech feedback, (2) compare and contrast synchronous and asynchronous self-generated and externally generated visual speech feedback, and (3) compare and contrast self-generated and externally generated visual speech feedback.