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1. Individual Differences in the Use of Acoustic-Phonetic Versus Lexical Cues for Speech Perception

   https://doi.org/10.3389/fcomm.2021.691225  

   Giovannone, Nikole; Theodore, Rachel M. (June 2021, Frontiers in Communication)

   null (Ed.)

   Previous research suggests that individuals with weaker receptive language show increased reliance on lexical information for speech perception relative to individuals with stronger receptive language, which may reflect a difference in how acoustic-phonetic and lexical cues are weighted for speech processing. Here we examined whether this relationship is the consequence of conflict between acoustic-phonetic and lexical cues in speech input, which has been found to mediate lexical reliance in sentential contexts. Two groups of participants completed standardized measures of language ability and a phonetic identification task to assess lexical recruitment (i.e., a Ganong task). In the high conflict group, the stimulus input distribution removed natural correlations between acoustic-phonetic and lexical cues, thus placing the two cues in high competition with each other; in the low conflict group, these correlations were present and thus competition was reduced as in natural speech. The results showed that 1) the Ganong effect was larger in the low compared to the high conflict condition in single-word contexts, suggesting that cue conflict dynamically influences online speech perception, 2) the Ganong effect was larger for those with weaker compared to stronger receptive language, and 3) the relationship between the Ganong effect and receptive language was not mediated by the degree to which acoustic-phonetic and lexical cues conflicted in the input. These results suggest that listeners with weaker language ability down-weight acoustic-phonetic cues and rely more heavily on lexical knowledge, even when stimulus input distributions reflect characteristics of natural speech input. 

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2. Lexical Information Guides Retuning of Neural Patterns in Perceptual Learning for Speech

   https://doi.org/10.1162/jocn_a_01612  

   Luthra, Sahil; Correia, João M.; Kleinschmidt, Dave F.; Mesite, Laura; Myers, Emily B. (October 2020, Journal of Cognitive Neuroscience)

   null (Ed.)

   Abstract A listener's interpretation of a given speech sound can vary probabilistically from moment to moment. Previous experience (i.e., the contexts in which one has encountered an ambiguous sound) can further influence the interpretation of speech, a phenomenon known as perceptual learning for speech. This study used multivoxel pattern analysis to query how neural patterns reflect perceptual learning, leveraging archival fMRI data from a lexically guided perceptual learning study conducted by Myers and Mesite [Myers, E. B., & Mesite, L. M. Neural systems underlying perceptual adjustment to non-standard speech tokens. Journal of Memory and Language, 76, 80–93, 2014]. In that study, participants first heard ambiguous /s/–/∫/ blends in either /s/-biased lexical contexts (epi_ode) or /∫/-biased contexts (refre_ing); subsequently, they performed a phonetic categorization task on tokens from an /asi/–/a∫i/ continuum. In the current work, a classifier was trained to distinguish between phonetic categorization trials in which participants heard unambiguous productions of /s/ and those in which they heard unambiguous productions of /∫/. The classifier was able to generalize this training to ambiguous tokens from the middle of the continuum on the basis of individual participants' trial-by-trial perception. We take these findings as evidence that perceptual learning for speech involves neural recalibration, such that the pattern of activation approximates the perceived category. Exploratory analyses showed that left parietal regions (supramarginal and angular gyri) and right temporal regions (superior, middle, and transverse temporal gyri) were most informative for categorization. Overall, our results inform an understanding of how moment-to-moment variability in speech perception is encoded in the brain. 

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3. Speech perception in younger and older adults: Cue-weighting and contextual information

   Cheng, R (September 2023, Proquest)

   This dissertation compared speech perception across younger and older normal-hearing adults. We ask four research questions to assess acoustic cue weighting and the role of contextual information (lexical information and speaking rate) in speech perception. Experiment 1 tested for age-related changes in cue-weighting. The absolute weights showed that older listeners relied on both VOT and F0 more than younger listeners, and some listeners’ reliance on VOT correlated with inhibitory control when perceiving the /d/-/t/ contrast. The relative weights suggested that older listeners relied on VOT less and F0 more than younger listeners. Experiment 2 tested whether younger and older listeners used different cue-weighting adjustment strategies in distributional learning. Both older and younger listeners adjusted their reliance on acoustic cues when the primary acoustic cue (VOT) became ambiguous. Older listeners adjusted F0 to a greater degree than younger listeners, while younger listeners adjusted VOT more than older listeners. With a lexically-guided learning paradigm, Experiment 3 explored if younger and older adults differed in their use of lexical information when learning to map acoustic tokens that were ambiguous. Older and younger listeners utilized the lexical context to the same extent. In Experiment 4, the contextual effect of speaking rate was examined by embedding voicing contrasts in short and long syllables and presenting these syllables to younger and older listeners. Older and younger listeners compensated for variation in speaking rate in a similar manner as younger listeners. The findings in perceptual learning demonstrate perceptual flexibility among normal-hearing older listeners, despite an assumed decline in temporal processing. 

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4. Rapid speech adaptation in younger and older normal-hearing adults: Distributional and lexically guided learning

   https://doi.org/10.1121/10.0011276  

   Cheng, Ruoqian; Jongman, Allard (April 2022, The Journal of the Acoustical Society of America)

   In speech perception, when a primary acoustic cue (e.g., VOT) is ambiguous, listeners may increase the weight of a secondary cue (e.g., F0). In experiment 1, we compared the cue-weighting adjustment strategies across younger and older normal-hearing adults with a distributional learning paradigm. Two groups of native English listeners were exposed to voicing contrasts that were ambiguous in either VOT or F0. Additionally, listeners may access lexical information to help resolve the ambiguity in the acoustic signal. Older listeners have been reported to use lexical information to a greater degree than younger listeners. In experiment 2, using a lexically guided learning paradigm, we tested if younger and older adults differ in their use of lexical information when learning to interpret ambiguous acoustic tokens. There were four types of exposure, in which stimuli differed in lexical status (day-*tay; *doy-toy) and the acoustic ambiguity involved either only VOT or both VOT and F0. Preliminary results from younger normal-hearing, listeners showed significant speech adaptation effects, with a significant change in cue weights in distributional learning and salient lexical bias in lexically guided learning. More data will be collected from older adults to assess the extent of perceptual learning relative to younger adults. 

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5. Examining the Relationship Between Multiple Tests of Receptive Vocabulary

   https://doi.org/10.1044/2023_JSLHR-22-00617  

   Harel, Daphna; Goudelias, Deanna; Cheng, Hung-Shao; Baese-Berk, Melissa M; Theodore, Rachel M; Levi, Susannah V (February 2024, Journal of Speech, Language, and Hearing Research)

   Purpose:Numerous tasks have been developed to measure receptive vocabulary, many of which were designed to be administered in person with a trained researcher or clinician. The purpose of the current study is to compare a common, in-person test of vocabulary with other vocabulary assessments that can be self-administered. Method:Fifty-three participants completed the Peabody Picture Vocabulary Test (PPVT) via online video call to mimic in-person administration, as well as four additional fully automated, self-administered measures of receptive vocabulary. Participants also completed three control tasks that do not measure receptive vocabulary. Results:Pearson correlations indicated moderate correlations among most of the receptive vocabulary measures (approximatelyr= .50–.70). As expected, the control tasks revealed only weak correlations to the vocabulary measures. However, subsets of items of the four self-administered measures of receptive vocabulary achieved high correlations with the PPVT (r> .80). These subsets were found through a repeated resampling approach. Conclusions:Measures of receptive vocabulary differ in which items are included and in the assessment task (e.g., lexical decision, picture matching, synonym matching). The results of the current study suggest that several self-administered tasks are able to achieve high correlations with the PPVT when a subset of items are scored, rather than the full set of items. These data provide evidence that subsets of items on one behavioral assessment can more highly correlate to another measure. In practical terms, these data demonstrate that self-administered, automated measures of receptive vocabulary can be used as reasonable substitutes of at least one test (PPVT) that requires human interaction. That several of the fully automated measures resulted in high correlations with the PPVT suggests that different tasks could be selected depending on the needs of the researcher. It is important to note the aim was not to establish clinical relevance of these measures, but establish whether researchers could use an experimental task of receptive vocabulary that probes a similar construct to what is captured by the PPVT, and use these measures of individual differences. 

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