Adults undertaking the endeavor of learning a new language can attest to the difficulty involved with producing the sounds and prosody of the target language. A principal aim of research on adult speech production is to comprehend the mechanisms and processes that differentiate adult bilingual speech development from bilingual speech that develops earlier in life. It is clear that individuals who learn an additional language in adulthood typically encounter some difficulties that early learners do not. In particular, these difficulties arise at the segmental level when acquiring novel sound categories and novel sound contrasts, as well as at the suprasegmental level when learning to produce non-native prosodic structures related to intonation, stress, rhythm, tone, and tempo. The present chapter provides a selective overview of the current state-of-the-art in adult bilingual speech production. Furthermore, this chapter considers theoretical and methodological areas for improvement, as well as avenues for future research.

Chapter 11 shows how linguistic experience plays a vital role in the perception and production of L2 speech sounds. The study presented in this chapter examines the differences between advanced English-speaking heritage language (HL) and non-heritage language (non-HL) learners of Korean by looking at their cross-linguistic categorization patterns and their degree of accuracy in identifying Korean stops. As predicted, based on the SLM, HL learners’ performance was more similar to the Korean native speakers than was non-HL learners’ performance. The results suggest that early exposure to the HL does indeed give an advantage to HL learners over their advanced non-HL counterparts, and that longer exposure to the target language for non-HL learners has a positive but limited role in obtaining a native-like perception of the three-way contrasts in Korean stops.