This methodological synthesis surveys study and instrument quality in L2 pronunciation research by scrutinizing methodological practices in designing and employing scales and rubrics that measure accentedness, comprehensibility, and intelligibility. A comprehensive coding scheme was developed, and searches were conducted in several databases. A total of 380 articles (409 samples) that employed 576 target instruments and appeared in peer-reviewed journals from 1977 to 2023 were synthesized. Results demonstrated, among other findings, strengths in reporting several listener and speaker characteristics. Areas in need of improvement include (a) more thorough evaluation and reporting of interrater reliability and instrument validity and (b) greater adherence to methodological transparency and open science practices. We conclude by discussing the implications of these findings for researchers and researcher trainers; by raising awareness of methodological and ethical challenges in psychometric research on L2 speech perception; and by providing recommendations for advancing the quality of instruments in this domain.

Adult heritage language (HL) speakers often exhibit subtle phonetic-phonological variations (“accentedness”) that diverge from the patterns of the language spoken at home. Perception of accentedness may also be influenced by the listener’s linguistic background. This study investigated perceived accentedness in 80 English speech samples from four groups of monolingual English and bilingual English-Hebrew speakers for whom English was either L1 or HL. These samples were evaluated by three rater groups: monolinguals, English-dominant bilinguals, and Hebrew-dominant bilinguals. Our findings confirmed the presence of slight accentedness in HL-English speakers and, to a lesser extent, in immigrants who acquired Hebrew as a second language. While rater background generally had minimal impact, English- and Hebrew-dominant bilinguals differed in their evaluations of the less-accented groups. Individual factors such as lexical proficiency and early language input influenced the HL-English speakers’ accentedness levels. The results are discussed in relation to the Critical Period Hypothesis and its implications.

This study examines the effects of task complexity on second language (L2) pronunciation accuracy and global pronunciation measures in pronunciation-unfocused tasks and assesses the relationship between acoustic and listener-based pronunciation measures. Eighty-two Catalan/Spanish learners of English performed simple and complex versions of a problem-solving monologic speaking task, for which the oral stops /p, t, k/ and vowel contrasts /iː/-/ɪ/ and /æ/-/ᴧ/ were embedded in the lexical items used to perform the task. Pronunciation accuracy was gauged through acoustic measurements of laryngeal timing (voice onset time), vowel contrastiveness and nativelikeness (Mahalanobis distances), and native speakers’ ratings of comprehensibility and accentedness. Results revealed detrimental effects of increased task complexity on the productions of oral stops and speech comprehensibility and accentedness; however, no consistent task complexity effects were found on vowel accuracy. The analysis also revealed an association between segmental accuracy and global dimensions of L2 speech.

The current project investigated the extent to which several lexical aspects of second language (L2) speech – appropriateness, fluency, variation, sophistication, abstractness, sense relations – interact to influence native speakers’ judgements of comprehensibility (ease of understanding) and accentedness (linguistic nativelikeness). Extemporaneous speech elicited from 40 French speakers of English with varied L2 proficiency levels was first evaluated by 10 native-speaking raters for comprehensibility and accentedness. Subsequently, the dataset was transcribed and analyzed for 12 lexical factors. Various lexical properties of L2 speech were found to be associated with L2 comprehensibility, and especially lexical accuracy (lemma appropriateness) and complexity (polysemy), indicating that these lexical variables are associated with successful L2 communication. In contrast, native speakers’ accent judgements seemed to be linked to surface-level details of lexical content (abstractness) and form (variation, morphological accuracy) rather than to its conceptual and contextual details (e.g., lemma appropriateness, polysemy).