Since Swain's (1985) Output Hypothesis, producing output in second language (L2) has been assumed to be a crucial cognitive process that promotes L2 acquisition, by actively facilitating various cognitive processes (e.g., noticing, hypothesis testing, conscious reflections of own language use, and automatization of the linguistic knowledge) (de…

Purpose: This study investigated the efficacy of ultrasound biofeedback compared to a traditional acoustic input-only method in the second-language (L2) production training of English tense-lax vowel contrasts (/i-[near-close near-front unrounded vowel]/ and /e-[open-mid front unrounded vowel]/). The relationship between the degrees of production…