Neural oscillations contribute to speech parsing via cortical tracking of hierarchical linguistic structures, including syllable rate. While the properties of neural entrainment have been largely probed with speech stimuli at either normal or artificially accelerated rates, the important case of natural fast speech has been largely overlooked. Using magnetoencephalography, we found that listening to naturally-produced speech was associated with cortico-acoustic coupling, both at normal (∼6 syllables/s) and fast (∼9 syllables/s) rates, with a corresponding shift in peak entrainment frequency. Interestingly, time-compressed sentences did not yield such coupling, despite being generated at the same rate as the natural fast sentences. Additionally, neural activity in right motor cortex exhibited stronger tuning to natural fast rather than to artificially accelerated speech, and showed evidence for stronger phase-coupling with left temporo-parietal and motor areas. These findings are highly relevant for our understanding of the role played by auditory and motor cortex oscillations in the perception of naturally produced speech.

神经振荡通过对分层语言结构（包括音节率）的皮层跟踪来促进语音解析。虽然神经夹带的特性在很大程度上已通过正常或人工加速的语音刺激进行了探索，但自然快速语音的重要案例在很大程度上被忽视了。使用脑磁图，我们发现在正常（~6 音节/秒）和快速（~9 音节/秒）速率下，聆听自然产生的语音与皮质声耦合相关，峰值夹带频率有相应的变化。有趣的是，时间压缩的句子并没有产生这种耦合，尽管它的生成速度与自然快速句子相同。此外，右侧运动皮层的神经活动表现出对自然快速而非人工加速语音的更强调谐，并显示出与左侧颞顶叶和运动区域更强的相位耦合的证据。这些发现与我们理解听觉和运动皮层振荡在自然产生的语音感知中所起的作用高度相关。