Department of Experimental Psychology, Division of Psychology and Language Sciences, University College London, London, WC1H 0AP, England.
Department of Speech, Hearing and Phonetic Sciences, Division of Psychology and Language Sciences, University College London, London, WC1N 1PF, England.
J Acoust Soc Am. 2018 Mar;143(3):1333. doi: 10.1121/1.5024340.
Speech-in-noise (SPIN) perception involves neural encoding of temporal acoustic cues. Cues include temporal fine structure (TFS) and envelopes that modulate at syllable (Slow-rate ENV) and fundamental frequency (F-rate ENV) rates. Here the relationship between speech-evoked neural responses to these cues and SPIN perception was investigated in older adults. Theta-band phase-locking values (PLVs) that reflect cortical sensitivity to Slow-rate ENV and peripheral/brainstem frequency-following responses phase-locked to F-rate ENV (FFR) and TFS (FFR) were measured from scalp-electroencephalography responses to a repeated speech syllable in steady-state speech-shaped noise (SpN) and 16-speaker babble noise (BbN). The results showed that (1) SPIN performance and PLVs were significantly higher under SpN than BbN, implying differential cortical encoding may serve as the neural mechanism of SPIN performance that varies as a function of noise types; (2) PLVs and FFR at resolved harmonics were significantly related to good SPIN performance, supporting the importance of phase-locked neural encoding of Slow-rate ENV and TFS of resolved harmonics during SPIN perception; (3) FFR was not associated to SPIN performance until audiometric threshold was controlled for, indicating that hearing loss should be carefully controlled when studying the role of neural encoding of F-rate ENV. Implications are drawn with respect to fitting auditory prostheses.
语音噪声比（SPIN）感知涉及到对时间声学线索的神经编码。线索包括时间精细结构（TFS）和调制在音节（慢速率 ENV）和基频（F 速率 ENV）速率的包络。在这里，研究了老年人对这些线索的语音诱发神经反应与 SPIN 感知之间的关系。反映对慢速率 ENV 皮质敏感性的θ波段锁相值（PLVs）以及与 F 速率 ENV（FFR）和 TFS（FFR）锁相的外周/脑干频率跟随反应（FFR），是从头皮脑电图对稳态语音噪声（SpN）和 16 个说话者背景噪声（BbN）中的重复语音音节的反应中测量的。结果表明：（1）在 SpN 下，SPIN 性能和 PLVs 显著高于 BbN，这意味着不同的皮质编码可能是 SPIN 性能的神经机制，其随着噪声类型的变化而变化；（2）PLVs 和在可分辨谐波上的 FFR 与良好的 SPIN 性能显著相关，支持在 SPIN 感知过程中，可分辨谐波的慢速率 ENV 和 TFS 的锁相神经编码的重要性；（3）在控制听力阈值后，FFR 与 SPIN 性能无关，这表明在研究 F 速率 ENV 的神经编码作用时，应仔细控制听力损失。这对听觉假体的适配提出了一些启示。
