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Abstract:The magnitude of anterior and dorsal constrictions for laterals in /(C)(C)VlC/ words produced by eight American English speakers was measured using ultrasound imaging. The results replicate previous findings that laterals have weaker anterior constrictions when followed by labial or velar consonants than when followed by alveolar consonants. The main novel finding is that, in words with /VlC labial / or /VlC velar / sequences, this anterior constriction was weaker in high-frequency words (help, milk) than in low-frequency words (whelp, ilk). Although high-frequency words also showed slight reduction of the dorsal constriction, dorsal reduction was stable, small in magnitude, and not correlated with anterior reduction, consistent with alveolar reduction not being simply a consequence of overall weaker lingual constrictions in more frequent words. Acoustic measures for laterals showed that the degree of anterior constriction correlated with the frequency separation between F1 and F2: more reduced alveolar constrictions -especially likely in high-frequency words -were linked with greater formant proximity. These articulatory and acoustic patterns are interpreted as potentially contributing to the initiation and lexical diffusion of historical /l/ lenition. It is proposed that gestural reduction in high-frequency words in which the anterior gesture for laterals must be coordinated with another supralaryngeal constriction serves as a precipitating factor in /l/ vocalization and possibly (although to a lesser extent) /l/ loss.

The disparity in the production and perception of children's singleton onset /l/s is linked to both physiological and phonological development. Suggestions are made for future research to tease these factors apart.

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Speech research using lingual ultrasound often requires both the ultrasound images as well as audio from the corresponding audio speech signals, but synchronization of these signals is not always available. We propose that periods of matching rates of change in the two signals could be used to align articulatory and acoustic signals where synchronization is impossible or would otherwise benefit from verification. In this study, we analyze pre-synchronized ultrasound and audio recordings of English speakers reading words. For each recording, we calculated the articulatory change as the change in pixel brightness values over time and the acoustic change as the change in Mel Frequency Cepstral Coefficient representations of the audio, and then calculated the degree of correlation between the acoustic and articulatory change over a window shifting through the recording. Then, we deliberately offset the signals in increments of 5 ms to verify that the known synchronization results in the best correlations. We manipulated several other variables, and preliminary results suggest that shorter window lengths and analyzing correlations only during detected speech result in the most accurate alignments. Analysis is ongoing to determine whether duration of correlation (number of windows with high r-values) or overall degree of correlation (median r-values) leads to the most accurate alignments.

Speakers monitor themselves while talking. When they hear a real-time altered version of their speech, they will change their articulation so that when they hear their altered speech, it matches their acoustic target [Houde and Jordan (1998, Science 20;279(5354):1213–1216)]. The experiment presented here used the novel addition of ultrasound imaging to reveal how speakers (n = 30) change their articulations in response to two different formant perturbations: raising of F1 in “head” and F2 in “hood.” Principal components analysis was used to identify speakers' individual strategies during adaptation. Some speakers use a single strategy for an entire adaptation block, while others change strategy. Speakers are also known to change production in a formant that was not altered [Katseff et al. (2010, JASA 127(3), 1955)]. The ultrasound analysis shows that at least for some speakers, change in two formants is linked to independent and uncorrelated articulatory components and possibly serves a perceptual purpose in compensation, rather than being an unintended result of the compensatory response. Preliminary results (n = 4) of adaptation to raising F3 in “heard” will also be presented. Modeling with the Maeda and Manzara synthesizers [Bakst and Johnson (2016, JASA 140(4), 3223)] correctly predicted speakers' articulatory strategies.

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Designers and engineers increasingly engage with and must design for sociotechnical systems, also described as cyber-physical-social systems (CPSS). Leading frameworks like System-Theoretic Process Analysis and Value-Sensitive Design intend to help designers consider the consequences and impacts of their work with CPSS. However, such frameworks may not sufficiently account for human-centered scenarios. This complicates designers’ efforts to balance user needs with traditional forms of risk assessment. In this work, we explore foundations for the design of human-centered risk frameworks and examine a case study of autonomous vehicles and bystanders’ privacy as an example CPSS to address this gap. We develop an exploratory scenario-based risk framework and conduct expert interviews with experienced professionals (N = 7) working in the fields of autonomous vehicle design, development, policy and security to understand their perspectives on risk assessment and gather feedback on our framework. Reconciling interview findings with existing knowledge of evolving CPSS, we identify three broad knowledge gaps that could motivate future research in this space. First, we argue that there is a knowledge gap in developing human-centered frameworks and best practices to consider all stakeholders during the design of evolving CPSS. Second, we argue that a knowledge gap exists in acknowledging, reconciling, and proactively managing disciplinary discontinuities in vocabularies and mental models in evolving CPSS. Lastly, we argue that a critical knowledge gap exists around how to adapt scenario-based frameworks to accommodate the shifting challenges of designing evolving CPSS. We conclude with a discussion of preliminary implications for designing human-centered frameworks for autonomous vehicles and CPSS more generally.