Toyomura Akira, Miyashiro Daiki, Kuriki Shinya, Sowman Paul F
Graduate School of Health Sciences, Gunma University, Maebashi, Japan.
Faculty of Medicine, School of Health Sciences, Gunma University, Maebashi, Japan.
Front Hum Neurosci. 2020 Apr 24;14:150. doi: 10.3389/fnhum.2020.00150. eCollection 2020.
Speech-induced suppression is the normal, relative amplitude reduction of the auditory evoked potential for self-, compared to externally-generated, auditory stimulation. It remains controversial as to whether adults who stutter exhibit expected auditory modulation during speech; some studies have reported a significant difference between stuttering and fluent groups in speech-induced suppression during speech movement planning, while others have not. We compared auditory evoked potentials (N1 component) for auditory feedback arising from one's own voice (Speaking condition) with passive listening to a recording of one's own voice (Listening condition) in 24 normally-fluent speakers and 16 adults who stutter under various delayed auditory feedback (DAF) time conditions (100 ms, 200 ms, 500 ms, and 1,000 ms). We presented the participant's own voice with a delay, immediately after presenting it without a delay. Our working hypothesis was that the shorter the delay time, the more likely the delayed sound is perceived as self-generated. Therefore, shorter delay time conditions are proposed to result in relatively enhanced suppression of the auditory system. Results showed that in fluent speakers, the shorter the delay time, the more the auditory evoked potential in the Speaking condition tended to be suppressed. In the Listening condition, there was a larger evoked potential with shorter delay times. As a result, speech-induced suppression was only significant at the short delay time conditions of 100 and 200 ms. Adults who stutter did not show the opposing changes in the Speaking and Listening conditions seen in the fluent group. Although the evoked potential in the Listening condition tended to decrease as the delay time increased, that in the Speaking condition did not show a distinct trend, and there was a significant suppression only at 200 ms delay. For the 200 ms delay condition, speakers with more severe stuttering showed significantly greater speech-induced suppression than those with less severe stuttering. This preliminary study suggests our methods for investigating evoked potentials by presenting own voice with a delay may provide a clue as to the nature of auditory modulation in stuttering.
言语诱发抑制是指与外部产生的听觉刺激相比，自我产生的听觉诱发电位的正常相对幅度降低。口吃的成年人在言语过程中是否表现出预期的听觉调制仍存在争议；一些研究报告称，在言语运动计划过程中，口吃组和流畅组在言语诱发抑制方面存在显著差异，而另一些研究则未发现此差异。我们比较了24名正常流畅说话者和16名口吃成年人在各种延迟听觉反馈（DAF）时间条件（100毫秒、200毫秒、500毫秒和1000毫秒）下，自己声音产生的听觉反馈（说话条件）与被动聆听自己声音录音（聆听条件）时的听觉诱发电位（N1成分）。我们在无延迟呈现参与者自己的声音后，立即延迟呈现。我们的工作假设是，延迟时间越短，延迟声音越有可能被视为自我产生的。因此，较短的延迟时间条件被认为会导致听觉系统的抑制相对增强。结果表明，在流畅说话者中，延迟时间越短，说话条件下的听觉诱发电位被抑制的程度越高。在聆听条件下，延迟时间越短，诱发电位越大。因此，言语诱发抑制仅在100毫秒和200毫秒的短延迟时间条件下显著。口吃的成年人在说话和聆听条件下并未表现出流畅组中所见的相反变化。虽然聆听条件下的诱发电位倾向于随着延迟时间的增加而降低，但说话条件下的诱发电位没有明显趋势，仅在200毫秒延迟时存在显著抑制。对于200毫秒延迟条件，口吃较严重的说话者比口吃较轻的说话者表现出明显更大的言语诱发抑制。这项初步研究表明，我们通过延迟呈现自己声音来研究诱发电位的方法可能为口吃的听觉调制性质提供线索。
