The effect of age on English /r/-/l/ perceptual training outcomes for Japanese speakers

Younger learners are better at acquiring second-language (L2) phoneme contrasts than are older learners, but this general correlation between age and learning ability is often confounded with factors such as how late learners use their L2 in daily life. The present study trained Japanese speakers across a wide age range (young children through adults) on English /r/-/l/, using a computer-based high variability phonetic training program, in order to control the /r/-/l/ inputs across age during the training period. The results demonstrated that training improved Japanese speakers’ perception and production of the English /r/-/l/ contrast, and age affected their improvement in perception. Over the 10 training sessions, younger learners (children and adolescents) improved their perception more than adult learners, suggesting that L2 phoneme learning may indeed decline with age. Children did not improve their identification, perceptual sensitivity to the primary acoustic cue (F3), and category discrimination as much as adolescents, possibly due to their immature cognition and phonemic awareness.