Okayasu Tadao, Nishimura Tadashi, Uratani Yuka, Yamashita Akinori, Nakagawa Seiji, Yamanaka Toshiaki, Hosoi Hiroshi, Kitahara Tadashi
Department of Otolaryngology-Head and Neck Surgery, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan.
Center for Frontier Medical Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan; Department of Medical Engineering, Graduate School of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan; University Hospital Med-Tech Link Center, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan; Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan.
Neurosci Lett. 2019 Mar 23;696:1-6. doi: 10.1016/j.neulet.2018.11.035. Epub 2018 Nov 23.
Bone-conducted ultrasound (BCU) can be heard for both normal-hearing and some profoundly deaf individuals. Moreover, amplitude-modulated BCU can transmit the speech signal. These characteristics of BCU provide the possibility of the developing a bone-conducted ultrasonic hearing aid. Previous studies on the perception mechanism of speech-modulated BCU have pointed to the importance of temporal rather than frequency information. In order to elucidate the perception of speech-modulated BCU, further investigation is need concerning the processing of temporal information. The temporal processing of air-conducted audible sounds (ACASs) involves the integration of closely presented sounds into a single information unit. The long-temporal window of integration was estimated approximately 150-200 ms, which contribute to the discrimination of speech sound. The present study investigated the long-temporal integration system for BCU evaluated by stimulus omission using magnetoencephalography. Eight participants with normal hearing took part in this study. Ultrasonic tone burst with the duration of 50 ms and frequency of 30 kHz was used as the standard stimulus and presented with steady onset-to-onset times or stimulus-onset asynchronies (SOAs). In each sequence, the duration of the SOAs were set to 100, 125, 150, 175, 200, or 350 ms. For deviant, tones were randomly omitted from the stimulus train. Definite mismatch fields were elicited by sound omission in the stimulus train with an SOA of 100-150 ms, but weren't with an SOA of 200 and 350 ms for all participants. We found that stimulus train for BCUs can be integrated within a temporal window of integration with an SOA of 100-150 ms, but are regarded as a separate event when the SOA is 200 or 350 ms in duration. Therefore, we demonstrated that the long-temporal window of integration for BCUs estimated by omission was 150-200 ms, which was similar to that for ACAS (Yabe et al. NeuroReport 8 (1997) 1971-1974 and Psychophysiology. 35 (1998) 615-619). These findings contribute to the elucidation and improvement of the perception of speech-modulated BCU.
正常听力者和一些极重度聋人都能听到骨传导超声（BCU）。此外，调幅BCU可以传输语音信号。BCU的这些特性为开发骨传导超声助听器提供了可能性。先前关于语音调制BCU感知机制的研究指出了时间信息而非频率信息的重要性。为了阐明语音调制BCU的感知，需要进一步研究时间信息的处理。气导可听声音（ACASs）的时间处理涉及将紧密呈现的声音整合为一个单一信息单元。整合的长时间窗口估计约为150 - 200毫秒，这有助于语音声音的辨别。本研究使用脑磁图通过刺激遗漏评估了BCU的长时间整合系统。八名听力正常的参与者参与了本研究。持续时间为50毫秒、频率为30千赫的超声脉冲串用作标准刺激，并以稳定的起始时间或刺激起始异步（SOA）呈现。在每个序列中，SOA的持续时间设置为100、125、150、175、200或350毫秒。对于偏差刺激，音调在刺激序列中随机遗漏。在SOA为100 - 150毫秒的刺激序列中，声音遗漏会引发明确的失配场，但对于所有参与者，在SOA为200和350毫秒时则不会。我们发现，BCU的刺激序列可以在100 - 150毫秒的SOA的整合时间窗口内整合，但当SOA持续时间为200或350毫秒时，它们被视为单独的事件。因此，我们证明通过遗漏估计的BCU的长时间整合窗口为150 - 200毫秒，这与ACAS的类似（矢部等人，《神经报告》8（1997年）1971 - 1974以及《心理生理学》。35（1998年）615 - 619）。这些发现有助于阐明和改善语音调制BCU的感知。
