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Purpose: The current study compared temporal and spectral acoustic contrast between vowel segments produced by speakers with dysarthria across three speech tasks--interactive, solo habitual, and solo clear. Method: Nine speakers with dysarthria secondary to amyotrophic lateral sclerosis participated in the study. Each speaker was paired with a typical interlocutor over videoconferencing software. The speakers produced the vowels /i, ..., ..., æ/ in / h/--vowel-/d/ words. For the solo tasks, speakers read the stimuli aloud in both their habitual and clear speaking styles. For the interactive task, speakers produced a target stimulus for their interlocutor to select among the four possibilities. We measured the duration difference between long and short vowels, as well as the F1/F2 Euclidean distance between adjacent vowels, and also determined how well the vowels could be classified based on their acoustic characteristics. Results: Temporal contrast between long and short vowels was higher in the interactive task than in both solo tasks. Spectral distance between adjacent vowel pairs was also higher for some pairs in the interactive task than the habitual speech task. Finally, vowel classification accuracy was highest in the interactive task. Conclusions: Overall, we found evidence that individuals with dysarthria produced vowels with greater acoustic contrast in structured interactions than they did in solo tasks. Furthermore, the speech adjustments they made to the vowel segments differed from those observed in solo speech. [ABSTRACT FROM AUTHOR]

Purpose: We present a tripartite view of intelligibility in which the contributions of both the speaker and listener, as well as their joint effort during interaction, are considered. While considerable research has examined communicative interactions in situ, there is a critical gap in current knowledge on how speech intelligibility unfolds during such interactions. Here, we argue that research examining speech intelligibility in communicative interactions may provide important groundwork for advancement in clinical interventions for individuals with dysarthria. Method: First, we describe the view and argue for its consideration as a powerful way of thinking about speech intelligibility. We then briefly situate the view in the relevant literature on speech intelligibility and existing theoretical frameworks. We then identify suitable methodological paradigms for studying joint contributions to intelligibility and, lastly, discuss the clinical application and potential impact of this tripartite view. Conclusions: Speech communication occurs through interaction; however, in the laboratory and clinic, emphasis is usually placed on individual speakers and listeners. We have proposed that it is critical to consider how the joint contributions of speakers and listeners affect speech intelligibility in communicative interaction. This conceptualization is well aligned with the International Classification of Functioning, Disability and Health, and the findings from such an approach will allow us to better understand how to maximize available resources to enhance speech intelligibility. [ABSTRACT FROM AUTHOR]

• Context influences the extent to which interlocutors phonetically converge. • Talker convergence is facilitated by increased task engagement. • Participant engagement can be enhanced by the use of video game task environments. Phonetic convergence is the process by which interlocutors' speech becomes more similar to each other during an interaction. Talker factors like sex, race, and conversational role appear to influence convergence. Yet, findings vary in how these factors impact convergence and which acoustic features talkers converge on. There is also evidence that task differences may contribute to this variability. The present study investigated how task engagement influences phonetic convergence. Participant dyads worked together to complete a series of word-matching puzzles in either a highly engaging task (navigating a virtual world in the computer game Minecraft™) or a less engaging task (clicking on the words from a list). On a given block, one participant (the director) was given a list of words to tell the other participant (the matcher), who used the words to complete a series of puzzles. Thirty word-initial monosyllabic voicing minimal pairs served as stimuli, and we measured the degree to which phonetic features of voicing (VOT, vowel length, F1 onset, and f0 onset) changed over the course of the experiment. Convergence was inconsistent for VOT. However, we found that task engagement affected convergence for secondary voicing features (F1 onset and vowel length), such that convergence was only observed among interlocutors in the high engagement task for these acoustic dimensions. These findings suggest that the extent of phonetic convergence on certain acoustic features can be influenced by how engaged participants are with their task environment. [Display omitted] [ABSTRACT FROM AUTHOR]

• Talkers adjust their speech dynamically when miscommunication arises. • Communicative context can influence speech adaptation processes. • Faux computer training paradigms are a useful tool for investigating clear speech. During conversation, talkers may adapt their speech in a variety of ways. One form of adaptation is clear speech , in which a talker hyperarticulates when faced with specific communication challenges. In this study, we investigated how phonetic adaptation is affected by the nature of apparent miscommunication. To do so, we utilized a common feature of American English dialects, in which intervocalic /t/ is realized as a voiced flap rather than an unvoiced, fully articulated stop before unstressed syllables, causing words like petal and pedal to sound similar. Flapped /t/ may become more distinct compared to /d/ during clear speech. Using a faux-computer training paradigm, we provided artificial feedback on subjects' speech. When subjects said a word (e.g., petal) the computer would either interpret the word correctly (i.e., it guesses petal) or incorrectly (it guesses pedal, kettle or ???). We measured talkers' produced word length, initial-syllable vowel length, and medial consonant stop closure or flap consonant duration in both their first and second utterances of each trial. We found that participants produced longer words, vowels, and stop closure durations in response to feedback that contained an error compared to correct feedback. Participants also changed their flapped productions to stops most often and lengthened their stop closures to a greater degree following voicing errors compared to the other error conditions. Our findings indicate that interlocutors' productions may change along different acoustic dimensions depending on the kind of miscommunication they experience. Broadly, our findings indicate a need to consider how phonetic adaptation in the form of clear speech is affected by the nature of miscommunication during conversational interaction. Graphical Abstract [Display omitted]. [ABSTRACT FROM AUTHOR]