Department of Speech, Language, and Hearing Sciences, University of Connecticut, Storrs, Mansfield, CT 06269, USA.
Department of Brain and Cognitive Sciences, University of Rochester, Rochester, NY 14627, USA.
Brain Lang. 2021 Jul;218:104959. doi: 10.1016/j.bandl.2021.104959. Epub 2021 Apr 28.
Phonetic categories have undefined edges, such that individual tokens that belong to different speech sound categories may occupy the same region in acoustic space. In continuous speech, there are multiple sources of top-down information (e.g., lexical, semantic) that help to resolve the identity of an ambiguous phoneme. Of interest is how these top-down constraints interact with ambiguity at the phonetic level. In the current fMRI study, participants passively listened to sentences that varied in semantic predictability and in the amount of naturally-occurring phonetic competition. The left middle frontal gyrus, angular gyrus, and anterior inferior frontal gyrus were sensitive to both semantic predictability and the degree of phonetic competition. Notably, greater phonetic competition within non-predictive contexts resulted in a negatively-graded neural response. We suggest that uncertainty at the phonetic-acoustic level interacts with uncertainty at the semantic level-perhaps due to a failure of the network to construct a coherent meaning.
语音类别具有不明确的边界，因此属于不同语音类别 的单个音位可能占据声学空间的相同区域。在连续语音中，存在多种自上而下的信息源（例如词汇、语义），有助于确定模糊音位的身份。感兴趣的是这些自上而下的约束条件如何与语音水平的模糊性相互作用。在当前的 fMRI 研究中，参与者被动地听了句子，这些句子在语义可预测性和自然发生的语音竞争程度上有所不同。左额中回、角回和额下回前部对语义可预测性和语音竞争程度都很敏感。值得注意的是，在非预测性语境中，语音竞争越大，神经反应呈负梯度。我们认为，语音-声学水平的不确定性与语义水平的不确定性相互作用——这可能是由于网络未能构建连贯的意义。
