Abstract: Humans are excellent learners. Yet, a notable and well-documented exception is the acquisition of non-native speech categories by adults. Speech category learning is supported by multiple systems and, as we learn more about these systems, it is becoming possible to improve perceptual behavior in adult learners. In this talk, which reflects on my postdoctoral work with Bharath Chandrasekaran’s team, I will discuss two potential ways to ameliorate second language acquisition of lexical tones: 1) high-variability training with trial-by-trial feedback and 2) sub-perceptual threshold peripheral nerve stimulation. Throughout this talk, I will show how these techniques can be used to enhance the neural coding and perceptual categorization of lexical tones in adult learners.