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1. Perceptual consequences of native and non-native clear speech

   https://doi.org/10.1121/10.0009403  

   Kato, Misaki; Baese-Berk, Melissa M. (February 2022, The Journal of the Acoustical Society of America)

   Native talkers are able to enhance acoustic characteristics of their speech in a speaking style known as “clear speech,” which is better understood by listeners than “plain speech.” However, despite substantial research in the area of clear speech, it is less clear whether non-native talkers of various proficiency levels are able to adopt a clear speaking style and if so, whether this style has perceptual benefits for native listeners. In the present study, native English listeners evaluated plain and clear speech produced by three groups: native English talkers, non-native talkers with lower proficiency, and non-native talkers with higher proficiency. Listeners completed a transcription task (i.e., an objective measure of the speech intelligibility). We investigated intelligibility as a function of language background and proficiency and also investigated the acoustic modifications that are associated with these perceptual benefits. The results of the study suggest that both native and non-native talkers modulate their speech when asked to adopt a clear speaking style, but that the size of the acoustic modifications, as well as consequences of this speaking style for perception differ as a function of language background and language proficiency. 

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2. A perceptual similarity space for speech based on self-supervised speech representations

   https://doi.org/10.1121/10.0026358  

   Chernyak, Bronya_R; Bradlow, Ann_R; Keshet, Joseph; Goldrick, Matthew (June 2024, The Journal of the Acoustical Society of America)

   Speech recognition by both humans and machines frequently fails in non-optimal yet common situations. For example, word recognition error rates for second-language (L2) speech can be high, especially under conditions involving background noise. At the same time, both human and machine speech recognition sometimes shows remarkable robustness against signal- and noise-related degradation. Which acoustic features of speech explain this substantial variation in intelligibility? Current approaches align speech to text to extract a small set of pre-defined spectro-temporal properties from specific sounds in particular words. However, variation in these properties leaves much cross-talker variation in intelligibility unexplained. We examine an alternative approach utilizing a perceptual similarity space acquired using self-supervised learning. This approach encodes distinctions between speech samples without requiring pre-defined acoustic features or speech-to-text alignment. We show that L2 English speech samples are less tightly clustered in the space than L1 samples reflecting variability in English proficiency among L2 talkers. Critically, distances in this similarity space are perceptually meaningful: L1 English listeners have lower recognition accuracy for L2 speakers whose speech is more distant in the space from L1 speech. These results indicate that perceptual similarity may form the basis for an entirely new speech and language analysis approach. 

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3. Precision communication: Physicians’ linguistic adaptation to patients’ health literacy

   https://doi.org/10.1126/sciadv.abj2836  

   Schillinger, Dean; Duran, Nicholas D.; McNamara, Danielle S.; Crossley, Scott A.; Balyan, Renu; Karter, Andrew J. (December 2021, Science Advances)

   Little quantitative research has explored which clinician skills and behaviors facilitate communication. Mutual understanding is especially challenging when patients have limited health literacy (HL). Two strategies hypothesized to improve communication include matching the complexity of language to patients’ HL (“universal tailoring”); or always using simple language (“universal precautions”). Through computational linguistic analysis of 237,126 email exchanges between dyads of 1094 physicians and 4331 English-speaking patients, we assessed matching (concordance/discordance) between physicians’ linguistic complexity and patients’ HL, and classified physicians’ communication strategies. Among low HL patients, discordance was associated with poor understanding ( P = 0.046). Physicians’ “universal tailoring” strategy was associated with better understanding for all patients ( P = 0.01), while “universal precautions” was not. There was an interaction between concordance and communication strategy ( P = 0.021): The combination of dyadic concordance and “universal tailoring” eliminated HL-related disparities. Physicians’ ability to adapt communication to match their patients’ HL promotes shared understanding and equity. The ‘Precision Medicine’ construct should be expanded to include the domain of ‘Precision Communication.’ 

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4. Eye Movement Traces of Linguistic Knowledge in Native and Non-Native Reading

   https://doi.org/10.1162/opmi_a_00084  

   Berzak, Yevgeni; Levy, Roger (January 2023, Open Mind)

   Abstract The detailed study of eye movements in reading has shed considerable light into how language processing unfolds in real time. Yet eye movements in reading remain inadequately studied in non-native (L2) readers, even though much of the world’s population is multilingual. Here we present a detailed analysis of the quantitative functional influences of word length, frequency, and predictability on eye movement measures in reading in a large, linguistically diverse sample of non-native English readers. We find many similar qualitative effects as in L1 readers, but crucially also a proficiency-sensitive “lexicon-context tradeoff”. The most proficient L2 readers’ eye movements approach an L1 pattern, but as L2 proficiency diminishes, readers’ eye movements become less sensitive to a word’s predictability in context and more sensitive to word frequency, which is context-invariant. This tradeoff supports a rational, experience-dependent account of how context-driven expectations are deployed in L2 language processing. 

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5. Characterization and normalization of second language speech intelligibility through lexical stress, speech rate, rhythm, and pauses

   https://doi.org/10.1121/10.0016224  

   Kang, Okim; Hirschi, Kevin; Hansen, John H.; Looney, Stephen (October 2022, The Journal of the Acoustical Society of America)

   While a range of measures based on speech production, language, and perception are possible (Manun et al., 2020) for the prediction and estimation of speech intelligibility, what constitutes second language (L2) intelligibility remains under-defined. Prosodic and temporal features (i.e., stress, speech rate, rhythm, and pause placement) have been shown to impact listener perception (Kang et al., 2020). Still, their relationship with highly intelligible speech is yet unclear. This study aimed to characterize L2 speech intelligibility. Acoustic analyses, including PRAAT and Python scripts, were conducted on 405 speech samples (30 s) from 102 L2 English speakers with a wide variety of backgrounds, proficiency levels, and intelligibility levels. The results indicate that highly intelligible speakers of English employ between 2 and 4 syllables per second and that higher or lower speeds are less intelligible. Silent pauses between 0.3 and 0.8 s were associated with the highest levels of intelligibility. Rhythm, measured by Δ syllable length of all content syllables, was marginally associated with intelligibility. Finally, lexical stress accuracy did not interfere substantially with intelligibility until less than 70% of the polysyllabic words were incorrect. These findings inform the fields of first and second language research as well as language education and pathology. 

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