This study investigates the effect of changes in voice onset time (VOT) on heritage speakers’ perception of Korean intervocalic stops (i.e., /p, t, k/), and compares their results to those of Korean monolinguals and second language (L2) learners of Korean who are L1 speakers of American English or Mandarin Chinese. A discrimination task using five synthetic /C1V1C2V2/ stimuli that differed in VOT of C2 was created to test inter-group differences. While the L2 learners display categorical awareness of VOT variation, Korean and heritage speakers perceive the two consonants to be the same for most stimuli regardless of VOT values. This unexpected lack of attention to VOT variation among heritage speakers suggests that they may switch their language mode to Korean and activate Korean phonology in discriminating non-phonemic VOT differences. However, their responses are not uniform or robust, with some showing a pattern similar to that of L2 learners, revealing strong individual differences among heritage speakers.

We examined the production and perception of voiced versus voiceless obstruents by thirty-three adolescent heritage speakers of Polish and Russian. First, a word list task was used to elicit the production of voiced and voiceless plosives in word-initial position. Voice onset time (VOT) values for both sets of stops were compared to the values reported for monolingual Polish and Russian speakers. To investigate the perception of phoneme contrasts in the heritage language, we used an auditory phoneme discrimination task that contained ten minimal pairs of real and nonce words with contrasting voiced and voiceless obstruents. The results showed an almost perfect perceptual discrimination and a separation of voiced and voiceless plosives in production; however, the VOT values differed significantly from those of monolinguals. Both groups showed convergence of VOT values towards the values reported for fortis and lenis stops in the majority language (i.e., German), leading to a non-native accent in the heritage language.

American Israelis are an understudied but regionally important population in Israel, who use American English as a heritage language. Most heritage language situations previously studied investigate low-status heritage languages rather than high-status heritage languages which function as languages of wider communication. Does the majority language (i.e., Modern Hebrew) influence the minority language (i.e., American English) in this unusual case, as predicted by previous research? This question is investigated through a picture-naming task comparing the speech acoustics of stop production in American English heritage speakers, American olim (i.e., immigrants), and native Hebrew speakers. Results reveal a heritage accent in Modern Hebrew rather than American English, with crosslinguistic influence from the minority language to the majority language. This unexpected result is explained using Flege and Bohn (2021)’s Revised Speech Learning Model (SLM-r), which argues that phones in a bilingual’s phonetic system are linked, allowing for, and even predicting, this type of crosslinguistic influence.

This chapter provides an overview of research on heritage language (HL) sound systems, with a focus on areas of convergence and divergence among heritage speakers (HSs), native speakers (NSs) who continue to be dominant in the language, and second language learners (L2ers) who acquired the language later in life. Drawing on data from a wide range of HLs, the chapter addresses both phonetic (articulatory, acoustic, perceptual) and phonological (phonemic, distributional, phonotactic) aspects of the HL sound system, as well as that of the majority language, in light of theories of bilingual speech and variables previously studied as predictors of HSs’ linguistic behavior. Despite the diversity of results reviewed, several recurring themes emerge, including intermediate patterning between NSs and L2ers, a higher level of performance in perception than production, and individual variability. In particular, the depth and the accessibility of HSs’ knowledge of the HL sound system show considerable variation related to structural linguistic factors, demographic and sociolinguistic factors, input and usage-based factors, and methodological factors. In addition to summarizing the areas in which there is an emerging consensus, the chapter points out a number of remaining questions that pave the way for future research on HL sound systems.