Beyond Static Measures: The Impact of Lexical Stress Error Categories on IELTS Spoken Proficiency

Abstract

Although current pedagogical practices and research recognize that lexical stress errors can affect proficiency scores, they have thus far treated such errors as a single category. This paper explored the impact of various categories of stress errors, as proposed in the English Word Stress Error Gravity Hierarchy (Ghosh & Levis, 2021), on IELTS spoken proficiency. Fifty‐seven L2 speakers completed two communicative tasks and were rated by experienced and trained raters using the IELTS rubric. Speakers' performances were subsequently phonetically analyzed and classified into different categories according to the lack/presence of accompanying vowel changes and the directionality of the stress shift. Results revealed that stress errors with vowel changes were linked to lower proficiency, but categories without vowel changes did not show a statistically significant relationship. Notably, the ratio of impactful stress errors only showed a significant decline with higher proficiency levels, suggesting a hierarchy of importance whereby lexical stress is only apparent once macro‐level features are established. Overall, it is argued that the current representation of lexical stress errors is oversimplified, and a dynamic operationalization of stress errors that considers the interaction between segmental and prosodic properties of stress is needed for an enhanced assessment of proficiency.