Department of Signal Processing and Acoustics, Aalto University, P.O. Box 12200, FI-00076, Finland.
Department of Signal Processing and Acoustics, Aalto University, P.O. Box 12200, FI-00076, Finland; Aalto Behavioral Laboratory, Aalto Neuroimaging, Aalto University, FI-00076, Finland.
Neuropsychologia. 2018 Jan 31;109:181-199. doi: 10.1016/j.neuropsychologia.2017.12.011. Epub 2017 Dec 14.
Perceptual prominence of linguistic units such as words has been earlier connected to the concepts of predictability and attentional orientation. One hypothesis is that low-probability prosodic or lexical content is perceived as prominent due to the surprisal and high information value associated with the stimulus. However, the existing behavioral studies have used stimulus manipulations that follow or violate typical linguistic patterns present in the listeners' native language, i.e., assuming that the listeners have already established a model for acceptable prosodic patterns in the language. In the present study, we investigated whether prosodic expectations and the resulting subjective impression of prominence is affected by brief statistical adaptation to suprasegmental acoustic features in speech, also in the case where the prosodic patterns do not necessarily follow language-typical marking for prominence. We first exposed listeners to five minutes of speech with uneven distributions of falling and rising fundamental frequency (F0) trajectories on sentence-final words, and then tested their judgments of prominence on a set of new utterances. The results show that the probability of the F0 trajectory affects the perception of prominence, a less frequent F0 trajectory making a word more prominent independently of the absolute direction of F0 change. In the second part of the study, we conducted EEG-measurements on a set of new subjects listening to similar utterances with predominantly rising or falling F0 on sentence-final words. Analysis of the resulting event-related potentials (ERP) reveals a significant difference in N200 and N400 ERP-component amplitudes between standard and deviant prosody, again independently of the F0 direction and the underlying lexical content. Since N400 has earlier been associated with semantic processing of stimuli, this suggests that listeners implicitly track probabilities at the suprasegmental level and that predictability of a prosodic pattern during a word has an impact to the semantic processing of the word. Overall, the study suggests that prosodic markers for prominence are at least partially driven by the statistical structure of recently perceived speech, and therefore prominence perception could be based on statistical learning mechanisms similar to those observed in early word learning, but in this case operating at the level of suprasegmental acoustic features.
语言单位（如单词）的感知突出程度与可预测性和注意力定向等概念有关。一种假设是，低概率韵律或词汇内容由于与刺激相关的意外和高信息价值而被感知为突出。然而，现有的行为研究使用了遵循或违反听众母语中存在的典型语言模式的刺激操作，即假设听众已经为语言中的可接受韵律模式建立了模型。在本研究中，我们调查了韵律期望以及由此产生的对突出程度的主观印象是否受到语音中超音段声学特征的短暂统计适应的影响，即使韵律模式不一定遵循语言典型的突出标记也是如此。我们首先让听众听五分钟的句子结尾词上的下降和上升基频（F0）轨迹分布不均匀的语音，然后测试他们对一组新句子的突出程度判断。结果表明，F0 轨迹的概率影响突出程度的感知，较少出现的 F0 轨迹使一个词更加突出，而与 F0 变化的绝对方向无关。在研究的第二部分，我们对一组新的听众进行了类似的句子结尾词上 F0 主要上升或下降的语音聆听，并进行了脑电测量。对产生的事件相关电位（ERP）的分析表明，标准和异常韵律之间的 N200 和 N400 ERP 分量幅度存在显著差异，这再次与 F0 方向和潜在的词汇内容无关。由于 N400 较早与刺激的语义处理有关，这表明听众在超音段水平上隐式地跟踪概率，并且一个词的韵律模式的可预测性对该词的语义处理有影响。总体而言，该研究表明，突出程度的韵律标记至少部分由最近感知的语音的统计结构驱动，因此突出程度感知可能基于与早期单词学习中观察到的类似的统计学习机制，但在这种情况下，它是在超音段声学特征的水平上运行的。
