Tones are the most challenging aspect of learning Chinese as a second language, and L2 learners? perceptual categories differ in important and fascinating ways from those of native speakers. This book explores the relationship between tone perception and production among native speakers and non-native learners as illustrated in the experiments the author conducted with native speakers, true learners and heritage learners, all of whom were tested on their ability to produce tones naturally and to perceive 81 synthesized tones in various contexts. The experiments show that each group processes tones differently with regard to both register (tonal level) and contour (tonal shape). The results also reveal how three types of cues ? acoustic, psychological and contextual ? influence non-native speakers? tone perception and production.