Systems Design Engineering

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Browsing Systems Design Engineering by Author "Ellag, Menatalla"

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    Assessment of Acoustic Markers of Conversational Difficulty
    (University of Waterloo, 2024-09-06) Ellag, Menatalla
    Human conversations, one of the most complex behaviors, require the real-time coordination of speech production and comprehension, involving cognitive, social, and biological dimensions. There has been a rising need for laboratory and clinical assessments to evolve to capture the essence of everyday interactions. The cognitive demands of interactive conversation, which require listeners to process and store information while simultaneously planning their responses, often exceed those encountered in standard clinical tests. These assessments must encompass diverse contexts and participant groups, including varying hearing statuses, challenging listening environments such as background noise, the use of assistive devices that may alter the listening experience, and different conversation types such as relational versus transactional exchanges, dyadic versus group interactions, and face-to-face versus remote interactions. This study consists of two investigations exploring how different conditions affect acoustic measures of speech production and conversational behavior. The first study was an extension of a study originally conducted for content analysis and participants’ subjective rating questionnaires, focusing on hearing-impaired (HI) individuals. It examined the impact of face masks and remote microphones on communication dynamics. Four native English-speaking HI participants engaged in free-form conversations within small groups under a constant background noise of 55 dBA. Interestingly, the results showed that using remote microphones shortened floor-transfer offsets (FTOs) and extended conversation durations, suggesting improved communication. When participants did not wear a face mask, interpausal unit (IPU) durations were shorter with remote microphones than without, indicating easier communication. However, no significant difference was found between the two mask conditions, suggesting that face masks affect both speech perception and production by decreasing inhalation and exhalation volumes, thereby limiting the duration of utterances. Face masks are speculated to increase resistance to airflow, reducing subglottal pressure and consequently lowering fundamental frequency (F0). Despite no significant differences in articulation rate and floor transfer rate, the constant noise environment, presented at lower levels compared to previous studies, may have likely limited the potential for pronounced effects. The second study involved normal-hearing (NH) individuals, investigating the effects of conversation type (free-form vs. task-based) and noise presence (70 dB SPL) on conversational dynamics. Dyadic interactions among NH participants were examined. Task-based conversations exhibited structured patterns with longer FTOs and higher floor transfer rates, while free-form conversations showed greater FTO variability, more frequent overlaps, longer IPUs, and increased pause durations and rates. Noise presence increased IPU durations and pause lengths but did not significantly alter floor-transfer rates or FTO variability. Both conversation types experienced increased articulation rates and speech levels in noise. Contrary to the expected change as part of the Lombard effect, the increase in articulation rates may be attributed to the noise acting as a stressor. Meanwhile, the increase in mean speech levels was less pronounced than expected, possibly due to the specific noise characteristics and the use of closed headphones. These studies shine a light on the complexity of communicative interactions and the necessity of accounting for a wide spectrum of factors in experimental designs. The findings highlight the importance of considering both environmental conditions and conversation types when researching speech perception, production, and conversational dynamics. This research provides valuable insights for academic studies and the development of hearing-assistive technologies, emphasizing the need for assessments that reflect the varied nature of everyday communication.