Is it possible to measure word-level comprehensibility and accentedness as independent constructs of pronunciation knowledge?

Abstract

The current study aims to explore the validity of measuring comprehensibility versus accentedness of L2 words as a construct of word pronunciation knowledge. Two research questions were addressed by investigating (a) the interrelationships among four listener-based measures (comprehensibility, accentedness, intelligibility, processing time) and (b) the relative contribution of linguistic features of L2 speech (segmental, word stress, rhythm, fluency) to comprehensibility and accentedness ratings. Nineteen native speakers of English rated L1 Japanese speakers’ productions of 37 English words elicited through a picture naming task for comprehensibility and accentedness. Two expert raters were recruited to complete a timed dictation task from which measures of intelligibility (orthographic transcription of L2 words) and processing time (how fast raters can initiate word transcription) were derived. The analyses of rating responses and relationships among listener-based measures showed that the current results were consistent with previous L2 speech studies measuring comprehensibility and accentedness at the sentence or paragraph level (Derwing and Munro, 2009). Three linguistic measures (segmental, word stress, rhythm) were significantly related to comprehensibility and accentedness ratings. The length of words (number of syllables) significantly predicted comprehensibility but not accentedness, indicating that longer words were easier to understand than shorter words. These findings provide initial evidence supporting the partial independence of comprehensibility and accentedness when L2 speech is measured at the word level. This study provides methodological implications for L2 vocabulary research and suggests using a word-level comprehensibility measure as an additional tool to gauge the employability of L2 words in real-life spoken communication.