Early and Late Stages of Neural Speech Processing in Native-English and Native-Polish Listeners: A Behavioral and ERP Study
Monica Wagner, St. John’s College of Liberal Arts and Sciences, Communication Sciences and Disorders
Abstract: The effect of exposure to contextual features of the cluster /pt/ on speech perception was investigated in native-English and native-Polish listeners using behavioral and ERP methodology. English and Polish listeners experience the cluster /pt/ in their languages, but only the Polish group experiences the cluster in the context examined in the current experiment (i.e., word onset). Acoustic features of phonemes change with context and, therefore, only the Polish listeners are exposed to the acoustic features of the word onset /pt/ cluster. Two and three-syllable nonsense words beginning with /pt/, p´t/, /st/ and /s´t/ were presented within same and different word pairs. A syllable identification task revealed that Polish listeners were able to distinguish /pt/ and /p´t/ nonsense words but English listeners were not, suggesting that contextual features of phonemes are intrinsic to perceptual speech processing. ERP responses to the second word in the pair revealed native-language speech perception to be reflected late in latency within the late positive component. The ERP response to the first word in the pairs revealed the P1N1P2 complex to the 2 and 3-syllable pt words to be highly similar for the English and Polish listeners. In contrast, English and Polish groups showed different responses from lateral-temporal sites (T-Complex) to the 2-syllable pt word forms reflecting native-language speech perception and these differences began early in cortical processing at 40 ms. Together, these findings suggest that both acoustic and linguistic distinctions are reflected at early stages of cortical speech processing but from different brain sources.