Hsieh I-Hui, Yeh Wan-Ting
Institute of Cognitive Neuroscience, National Central University, Taoyuan City, Taiwan.
Front Psychol. 2021 Mar 23;12:637289. doi: 10.3389/fpsyg.2021.637289. eCollection 2021.
Speech comprehension across languages depends on encoding the pitch variations in frequency-modulated (FM) sweeps at different timescales and frequency ranges. While timescale and spectral contour of FM sweeps play important roles in differentiating acoustic speech units, relatively little work has been done to understand the interaction between the two acoustic dimensions at early cortical processing. An auditory oddball paradigm was employed to examine the interaction of timescale and pitch contour at pre-attentive processing of FM sweeps. Event-related potentials to frequency sweeps that vary in linguistically relevant pitch contour (fundamental frequency F0 vs. first formant frequency F1) and timescale (local vs. global) in Mandarin Chinese were recorded. Mismatch negativities (MMNs) were elicited by all types of sweep deviants. For local timescale, FM sweeps with F0 contours yielded larger MMN amplitudes than F1 contours. A reversed MMN amplitude pattern was obtained with respect to F0/F1 contours for global timescale stimuli. An interhemispheric asymmetry of MMN topography was observed corresponding to local and global-timescale contours. Falling but not rising frequency difference waveforms sweep contours elicited right hemispheric dominance. Results showed that timescale and pitch contour interacts with each other in pre-attentive auditory processing of FM sweeps. Findings suggest that FM sweeps, a type of non-speech signal, is processed at an early stage with reference to its linguistic function. That the dynamic interaction between timescale and spectral pattern is processed during early cortical processing of non-speech frequency sweep signal may be critical to facilitate speech encoding at a later stage.
跨语言的言语理解取决于在不同时间尺度和频率范围内对调频（FM）扫描中的音高变化进行编码。虽然FM扫描的时间尺度和频谱轮廓在区分声学语音单元方面起着重要作用，但在早期皮层处理过程中，对于理解这两个声学维度之间的相互作用所做的工作相对较少。采用听觉Oddball范式来研究FM扫描的前注意处理过程中时间尺度和音高轮廓的相互作用。记录了与汉语中在语言相关的音高轮廓（基频F0与第一共振峰频率F1）和时间尺度（局部与全局）上变化的频率扫描相关的事件相关电位。所有类型的扫描偏差都引发了失配负波（MMN）。对于局部时间尺度，具有F0轮廓的FM扫描比具有F1轮廓的扫描产生更大的MMN振幅。对于全局时间尺度刺激，在F0/F1轮廓方面获得了相反的MMN振幅模式。观察到MMN地形图的半球间不对称对应于局部和全局时间尺度轮廓。下降而非上升的频率差波形扫描轮廓引发右半球优势。结果表明，在FM扫描的前注意听觉处理中，时间尺度和音高轮廓相互作用。研究结果表明，FM扫描这种非语音信号在早期阶段是根据其语言功能进行处理的。在非语音频率扫描信号的早期皮层处理过程中，时间尺度和频谱模式之间的动态相互作用可能对促进后期的语音编码至关重要。
