Effects of Practice Variability on Second-Language Speech Production Training

Background: Mastering the phonetics of a second language (L2) involves a component of speech-motor skill, and it has been suggested that L2 learners aiming to achieve a more native-like pronunciation could benefit from practice structured in accordance with the principles of motor learning. Participants and Methods: This study investigated the influence one such principle, high versus low variability in practice, has on speech-motor learning for Korean adults seeking to acquire native-like production of English rhotics. Practice incorporated a commercially available intraoral placement device ("R Buddy,"Speech Buddies Inc.). In a single-subject across-behaviors design, 8 participants were pseudorandomly assigned to practice rhotic targets in a low-variability (single word) or high-variability (multiple words) practice condition. Results: The hypothesized advantage for high-variability over low-variability practice was observed in the short-term time frame. However, long-term learning was limited in nature for both conditions. Conclusion: These results suggest that future research should incorporate high-variability practice while identifying additional manipulations to maximize the magnitude of long-term generalization learning.