Anyone with experience learning a new language likely knows something about the challenge of adapting to unfamiliar sounds. Tone languages like Mandarin Chinese present an interesting instance of this challenge. In Mandarin, pitch (F0) patterns on syllables are an integral part of words. For example, the syllable ma with a high-level tone is ‘mom’, with a rising tone is ‘hemp’, with a low tone is ‘horse’, and with a falling tone is ‘scold’. For learners from non-tonal language backgrounds, tones present several challenges: learners of course need to (1) hear the differences between tone categories (high, rising, low, falling), but they also need to treat these new categories as essential for word identity by (2) encoding them in memory, and (3) using them in real-time word recognition. Cute examples like ma might make it seem as if the integral nature of tones will be obvious to learners, but in practice syllables with a neat set of four-way tone contrasts are rare. For word recognition in natural speech, most tones on most words are neither necessary (due to context) nor sufficient (due to homophones).

With these thoughts in mind, I will present a series of behavioral and ERP studies examining the tone abilities of advanced (i.e., successful) L2 learners of Mandarin. How well do these successful L2 learners master tones and what difficulties, if any, do they encounter? We will see that advanced learners perform with virtually the same mastery as native speakers on challenging tone identification tasks, but that the introduction of minimal context (a second syllable) disproportionately affects learners. When it comes to (tone) word recognition, the same learners who excel at tone identification display wide variability. While some individuals excel, learners as a group are often insensitive to tone cues—even when they know the appropriate tones for the tested words. At the same time, learners often lack explicit tone knowledge for frequent words, suggesting they are not able to efficiently encode lexical tone representations in long-term memory. Nevertheless, as noted, all the learners included in this research are rightly described as successful. Considering this, I will finish by considering whether accurate L2 tone perception even matters at all.