Cortical Measures of Phoneme-Level Speech Encoding Correlate with the Perceived Clarity of Natural Speech.
Cortical Measures of Phoneme-Level Speech Encoding Correlate with the Perceived Clarity of Natural Speech.
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DOI：
10.1523/eneuro.0084-18.2018
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发表时间：
2018-03
期刊：
影响因子：
3.4
通讯作者：
Lalor EC
中科院分区：
文献类型：
--
作者：
Di Liberto GM;Crosse MJ;Lalor EC
在现实世界的环境中，人类通过主动整合先验知识（P）和预期与感官输入来理解语音。最近的研究揭示了先前信息在颞叶和额叶皮层区域的影响，并表明这些影响是由语音特定功能的增强编码所支撑的，而不是广泛的增强或抑制皮层活动。然而，就言语理解中涉及的特定层次处理阶段而言，整合自下而上的感觉反应和自上而下的预测的效果仍然不清楚。此外，还不清楚先前信息带来的可预测性是否会相对于该预测带来的感知增强而对语音编码产生不同的影响。研究这些问题的一种方法是通过检查P对连续语音特征的皮层跟踪指数的影响。在这里，我们通过向参与者提供退化的语音句子来做到这一点，这些句子之前有或没有清晰的记录，同时记录非侵入性脑电图（EEG）。我们评估了先前信息对反映音素级处理的皮层跟踪孤立指数的影响。我们的研究结果表明，先验信息影响自然语音的早期编码的双重方式的可能性。首先，先验信息的可用性，假设，提高了感知清晰度的退化语音，这是正相关的音素水平编码的变化，跨学科。此外，P诱导的皮质测量，我们解释为增加可预测性的结果的整体减少。
In real-world environments, humans comprehend speech by actively integrating prior knowledge (P) and expectations with sensory input. Recent studies have revealed effects of prior information in temporal and frontal cortical areas and have suggested that these effects are underpinned by enhanced encoding of speech-specific features, rather than a broad enhancement or suppression of cortical activity. However, in terms of the specific hierarchical stages of processing involved in speech comprehension, the effects of integrating bottom-up sensory responses and top-down predictions are still unclear. In addition, it is unclear whether the predictability that comes with prior information may differentially affect speech encoding relative to the perceptual enhancement that comes with that prediction. One way to investigate these issues is through examining the impact of P on indices of cortical tracking of continuous speech features. Here, we did this by presenting participants with degraded speech sentences that either were or were not preceded by a clear recording of the same sentences while recording non-invasive electroencephalography (EEG). We assessed the impact of prior information on an isolated index of cortical tracking that reflected phoneme-level processing. Our findings suggest the possibility that prior information affects the early encoding of natural speech in a dual manner. Firstly, the availability of prior information, as hypothesized, enhanced the perceived clarity of degraded speech, which was positively correlated with changes in phoneme-level encoding across subjects. In addition, P induced an overall reduction of this cortical measure, which we interpret as resulting from the increase in predictability.