Second language speech comprehensibility and acceptability in academic settings: Listener perceptions and speech stream influences

TL;DR: Comprehensible L2 speech is generally perceived as acceptable in academic settings. Speech stream characteristics have a significant impact on judgments of both comprehensibility and acceptability.

Abstract: Abstract Ideally, comprehensible second language (L2) speech would be seen as acceptable speech. However, the association between these dimensions is underexplored. To investigate the relationship between comprehensibility and “academic acceptability,” defined here as how well a speaker could meet the demands of a given role in an academic setting, 204 university stakeholders judged L2 speech samples elicited from a standardized English test used for university admissions. Four tasks from 100 speakers were coded for 13 speech stream characteristics. Judgments for comprehensibility and acceptability correlated strongly (r = .93). Linear mixed-effects models, used to examine judgments across all tasks and separately for each task, indicated that while random intercepts (i.e., speaker ability, listener severity) explained a substantial amount of total variation (32–44%) in listener judgments compared to speech characteristic fixed effects (8–21%), fixed effects did account for variation in speaker random effects (reducing variation compared to intercept-only models by 50–90%). Despite some minimal differences across task types, the influence of speech characteristics across both judgments was mostly similar. While providing evidence that comprehensible speech can indeed be perceived as acceptable, this study also provides evidence that speakers demonstrate both consistent and less consistent performance, in reference to speech stream production, across performances.