Koichi Mori

Functional lateralization of speech processing in adults and children who stutter.

Developmental stuttering is a speech disorder in fluency characterized by repetitions, prolongations, and silent blocks, especially in the initial parts of utterances. Although their symptoms are motor related, people who stutter show abnormal patterns of cerebral hemispheric dominance in both anterior and posterior language areas. It is unknown whether the abnormal functional lateralization in the posterior language area starts during childhood or emerges as a consequence of many years of stuttering. In order to address this issue, we measured the lateralization of hemodynamic responses in the auditory cortex during auditory speech processing in adults and children who stutter, including preschoolers, with near-infrared spectroscopy. We used the analysis–resynthesis technique to prepare two types of stimuli: (i) a phonemic contrast embedded in Japanese spoken words (/itta/ vs. /itte/) and (ii) a prosodic contrast (/itta/ vs. /itta?/). In the baseline blocks, only /itta/ tokens were presented. In phonemic contrast blocks, /itta/ and /itte/ tokens were presented pseudo-randomly, and /itta/ and /itta?/ tokens in prosodic contrast blocks. In adults and children who do not stutter, there was a clear left-hemispheric advantage for the phonemic contrast compared to the prosodic contrast. Adults and children who stutter, however, showed no significant difference between the two stimulus conditions. A subject-by-subject analysis revealed that not a single subject who stutters showed a left advantage in the phonemic contrast over the prosodic contrast condition. These results indicate that the functional lateralization for auditory speech processing is in disarray among those who stutter, even at preschool age. These results shed light on the neural pathophysiology of developmental stuttering.

Brain activation in adults who stutter under delayed auditory feedback: An fMRI study

It is well known that some people who stutter (PWS) show an immediate reduction of stuttering when they speak under a condition of delayed auditory feedback (DAF). In the present study, to investigate cortical activations during speech production through the DAF effect, we performed functional magnetic resonance imaging (fMRI) experiments under the NAF (non-altered feedback) and DAF conditions for PWS and people who do not stutter (PWNS). The results are that (1) the PWS showed the higher activation in the right inferior frontal gyrus (Brodmann Area (BA)45) than the PWNS under the NAF condition; (2) the activations of the right superior temporal gyrus and the right middle temporal gyrus were higher under the DAF condition than the NAF in both PWNS and PWS groups; (3) the PWNS showed the higher activation in the right supplementary motor area and superior temporal gyrus than the PWS under both NAF and DAF conditions; (4) the PWNS showed the higher activation in the inferior frontal gyrus(the right BA45 and the bilateral BA46) under the DAF condition than the NAF. These results reconfirm most of the previous findings with some slightly different activation areas, and underscore the involvement of inferior frontal gyrus and superior temporal gyrus in dysfluency.

An Overview of Managing Stuttering in Japan

PURPOSE The purpose of this article is to describe the rapid development of speech-language pathology in Japan since governmental licensing started in 1997 and to summarize the current trends in assessing and treating stuttering for preschoolers, school-age children, adolescents, and adults. METHOD The authors review relevant information about the current assessment and treatment services for people who stutter in Japan and discuss the issues and challenges faced by speech-language pathologists in managing stuttering. CONCLUSION It is predicted that as expertise in stuttering grows in Japan, the role of stuttering specialists in allied health, school districts, and research will increase.

Japanese normative data for the Unhelpful Thoughts and Beliefs about Stuttering (UTBAS) Scales for adults who stutter

PURPOSE This study reports Japanese normative data for the Unhelpful Thoughts and Beliefs about Stuttering (UTBAS) scales. We outline the translation process, and evaluate the psychometric properties of the Japanese version of the UTBAS scales. METHODS The translation of the UTBAS scales into Japanese (UTBAS-J) was completed using the standard forward-backward translation process, and was administered to 130 Japanese adults who stutter. To validate the UTBAS-J scales, scores for the Japanese and Australian cohorts were compared. Spearman correlations were conducted between the UTBAS-J and the Modified Erickson Communication Attitude scale (S-24), the self-assessment scale of speech (SA scale), and age. The test-retest reliability and internal consistency of the UTBAS-J were assessed. Independent t-tests were conducted to evaluate the differences in the UTBAS-J scales according to gender, speech treatment experience, and stuttering self-help group participation experience. RESULTS The UTBAS-J showed good test-retest reliability, high internal consistency, and moderate to high significant correlations with S-24 and SA scale. A weak correlation was found between the UTBAS-J scales with age. No significant relationships were found between UTBAS-J scores, gender and speech treatment experience. However, those who participated in the stuttering self-help group demonstrated lower UTBAS-J scores than those who did not. CONCLUSION Given the current scarcity of clinical assessment tools for adults who stutter in Japan, the UTBAS-J holds promise as an assessment tool and outcome measure for use in clinical and research environments.

Effect of the fundamental frequency and vocal register on the voice pitch compensation.

Fundamental frequency (F0) of our vocalization is regulated by auditory feedback. Manipulation of F0 in the auditory feedback invokes compensatory F0 response in vocalization, whose amplitude is known to depend on the task (singing or speaking; instruction to follow/ignore the heard pitch change) and the averaged F0. In order to exclude the voluntary factor and to test if the vocal register affected the response amplitude, we used a parametric modulation of F0 according to the maximal sequence [TAF, Kawahara (1992)] and recovered an impulse response with deconvolution during vowel phonation at various averaged F0 (low, at speech fundamental frequency, high) and in two vocal registers (modal and falsetto). The normalized response amplitude increased with F0, which replicates the previous finding, while the vocal register change did not affect the response. Our findings clarify some of the characteristics of tasks dependency of the pitch control.

Automatic Discrimination of Soft Voice Onset Using Acoustic Features of Breathy Voicing.

Soft onset vocalization is used in certain speech therapies. However, it is not easy to practice it at home because the acoustical evaluation itself needs training. It would be helpful for speech patients to get objective feedback during training. In this paper, new parameters for identifying soft onset with high accuracy are described. One of the parameters measures an aspect of the soft voice onset, in which the vocal folds start to oscillate periodically before coming in contact with each other at the beginning of vocalization. Combined with an onset time exceeding a threshold, the proposed parameters gave about 99% accuracy in identifying soft onset vocalization.

Effects of prosody on phoneme recognition in cochlear implant patients

KOICHI MORI, AKIHIRO TANAKA, National Rehabilitation Center for Persons with Disabilities, Tokorozawa-city, 359-8555, Japan TOSHIZO KOIZUMI, National Rehabilitation Center for Persons with Disabilities, Tokorozawa-city, 359-8555, Japan, and Department of Otorhinolaryngology, Nara Medical University, Kashihara-city, 634-8522, Japan HIKARU TAUCHI, National Rehabilitation Center for Persons with Disabilities, Tokorozawa-city, 359-8555, Japan