Inferior Frontal Cortex Contributions to the Recognition of Spoken Words and Their Constituent Speech Sounds

Rogers, Jack C. and Davis, Matthew H. (2017) Inferior Frontal Cortex Contributions to the Recognition of Spoken Words and Their Constituent Speech Sounds. Journal of Cognitive Neuroscience, 29 (5). pp. 919-936. ISSN 0898-929X

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Speech perception and comprehension are often challenged by the need to recognize speech sounds that are degraded or ambiguous. Here, we explore the cognitive and neural mechanisms involved in resolving ambiguity in the identity of speech sounds using syllables that contain ambiguous phonetic segments (e.g., intermediate sounds between /b/ and /g/ as in "blade" and "glade"). We used an audio-morphing procedure to create a large set of natural sounding minimal pairs that contain phonetically ambiguous onset or offset consonants (differing in place, manner, or voicing). These ambiguous segments occurred in different lexical contexts (i.e., in words or pseudowords, such as blade-glade or blem-glem) and in different phonological environments (i.e., with neighboring syllables that differed in lexical status, such as blouse-glouse). These stimuli allowed us to explore the impact of phonetic ambiguity on the speed and accuracy of lexical decision responses (Experiment 1), semantic categorization responses (Experiment 2), and the magnitude of BOLD fMRI responses during attentive comprehension (Experiment 3). For both behavioral and neural measures, observed effects of phonetic ambiguity were influenced by lexical context leading to slower responses and increased activity in the left inferior frontal gyrus for high-ambiguity syllables that distinguish pairs of words, but not for equivalent pseudowords. These findings suggest lexical involvement in the resolution of phonetic ambiguity. Implications for speech perception and the role of inferior frontal regions are discussed

Item Type: Article
Identification Number:
30 March 2017Published Online
22 November 2016Accepted
Subjects: CAH04 - psychology > CAH04-01 - psychology > CAH04-01-01 - psychology (non-specific)
Divisions: Faculty of Business, Law and Social Sciences > School of Social Sciences > Dept. Psychology
Depositing User: Silvio Aldrovandi
Date Deposited: 03 Apr 2018 16:20
Last Modified: 03 Mar 2022 15:42

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