This meta-analysis of 79 studies evaluates the effectiveness of high variability phonetic training (HVPT) for the development of second language (L2) speech perception and explores learner-related and methodological variables that influence training effects. The overall medium-to-large effects of HVPT on L2 speech perception support the effectiveness of HVPT, for both pretest-posttest comparison (g = 0.92, k = 96) and treatment-control comparison (g = 0.67, k = 32), confirm long-term retention of perception gains, and, to some extent, indicate generalization of learning to novel stimuli. Training effects are influenced by several key variables (length of L2 learning, response labels, type of training task, type of testing task, total training time, target phones, and number of talkers). The findings provide compelling evidence to support the efficacy of HVPT for L2 perceptual learning and suggest circumstances under which training effects are optimized.

High variability phonetic training using perceptual tasks such as identification and discrimination tasks has often been reported to improve L2 perception. However, studies comparing the efficacy of different tasks on different measures are rare. Forty-four Catalan/Spanish bilingual learners of English were trained with identification or categorical discrimination tasks and were tested on both measures. Results showed that both methods were successful in improving the identification and discrimination of English vowels. Training with nonword stimuli generalized to new nonwords and real word stimuli, and improvement was maintained four months later. Cross-task effects may be related to the categorical nature of the discrimination task, which may entail a level of processing similar to that of identification training. Interestingly, whereas identification training improved identification more than discrimination training, discrimination training did not enhance discrimination more than identification training. This asymmetry may be explained by task differences in the amount and type of feedback used.