Investigating L2 Phonological Acquisition from Different Perspectives: An Introduction to the Special Issue

Building on the existing literature including recent Special Issues, edited volumes, and feature articles on the study of second language (L2) phonetics and phonology (e.g., Archibald et al., 2021; Hansen-Edwards & Zampini, 2008; Nagle & Baese-Berk, 2022; Wayland, 2021), this Special Issue sets out to showcase the vibrant theoretical and empirical work that is being undertaken in this field of research. We aimed to attract contributions in different sub-domains of L2 phonetics and phonology including work that investigates the interface between different linguistic domains as well as across modalities.

It was also one of our aims to challenge the over-representation of the so-called WEIRD (Western, Educated, Industrialised, Rich, and Democratic) contexts in social sciences, applied linguistics, and, more specifically, in second language speech and phonology (see Leung, 2025) by including research from wider contexts and from participants who are under-represented. One group of second language learners that continues to be marginalised are adult immigrants with limited literacy. The wider SLA research community knows next to nothing about how the lack of literacy in one’s native or second language might affect the acquisition of phonology (see, e.g., Day, 2025). As others have commented (Young-Scholten, 2013), meeting this aim is not only an overall challenge but in phonetics and phonology, the challenge has resulted in almost no published research. We return to this challenge further below.

The resulting Special Issue presented here include studies which address, in part, the above aim for the inclusion of non-WEIRD study participants. The studies reported on involve less-common geographic locations in addition to Canada and the UK, (i.e., Bangladesh, Indonesia, and Vietnam); less-usual linguistic backgrounds in addition to English and Spanish (i.e., Bengali, Indonesian, Vietnamese, and Kazakh); different sub-domains of L2 phonetics and phonology (i.e., consonants, vowels), their interface with other linguistic domains (i.e., morpho-phonology), and modalities (i.e., orthography); and different methodological approaches and theoretical orientations. Below we provide a brief summary for each of the six contributions included in this Special Issue.

Utilising a longitudinal case study approach, Nulahan and Rose report on the acquisition of English consonants by a child Kazakh speaker. The phonemes /f, v, θ, ð, ɹ, ʃ, and ʧ/ were chosen as the focus as they are not part of the Kazakh phonological inventory. Through analysing naturally occurring home interaction data collected over the course of five months, their study revealed that the key participant’s acquisition varied across segments, making extremely rapid progress on some while making much slower progress on the others. Nulahan and Rose analysed their data through the Phonological Interference Hypothesis, which was recently extended into the Feature Redistribution and Recombination Hypothesis. They showed that while feature-based accounts were able to capture some of their observations, in some contexts, it is important to consider the phonetic characteristics.

Ingham’s study investigates the morpho-phonological interface. It attempted to account for the apparent asymmetrical production of the morpheme ‘-s’ in the marking of number on plural nouns versus that on third person singular agreement through analysing L2 English data by Bengali speakers of various proficiencies. Data collected via a semi-spontaneous elicited production test were analysed through a generative-based approach, i.e., the Prosodic Transfer Hypothesis (PTH). The PTH stipulates that the prosodic representation of inflectional morphology in the first language (L1) can, to some extent, account for differences in the suppliance of inflectional morphology in L2 English within and across L1s. Ingham also employed spectrogram analyses to explore the possibility that learners are supplying covert contrasts for their morphological markings.

Focusing on the potential interface across modalities, Shepperd’s article provides a review of recent work on cross-scriptal orthographic influence on L2 phonology. She pointed out that most of the existing literature on orthographic influence studied learning across languages that share the same orthographic script, often involving the Latin alphabet and English. She argued that this undermines our understanding of the potential influence of orthography. The initial evidence she reviews in her paper on cross-scriptal pairing suggests that even entirely unfamiliar written input impacts phonological learning and is certainly influential with growing proficiency in the spoken and written language. Shepperd concludes her article by highlighting some theoretical and methodological considerations for future research.

Anchored on the World Englishes paradigm and work on the Lingual Franca Core, Syam, Gardner, and Cribb analysed L2 English production data from educated Indonesians; the data were elicited through a reading task. By doing so, they provided descriptions of pronunciation features of Indonesian-Accented English (IAE). IAE consonants, clusters, and vowels were examined through acoustic analysis and spectrographic observation. They found that contrastive analyses of Indonesian and English did not predict all the IAE features that they identified, and that participants’ production for certain segments varies according to the syllable/ word position that the sounds occupy.

Kogan’s article investigates L1 phonetic category compactness (PCC) among Spanish speakers of various linguistic profiles. PCC pertains to the degree of variation or dispersion within a specific category. Her study explores the potential interaction among the compactness of L1 vowel categories, participants’ ability in another language, and the density of the phonological system. The category compactness in perception for Spanish vowels /i/, /e/, and /a/ was examined among four participant groups—monolinguals, functional monolinguals, bilinguals, and multilinguals. Findings from a vowel identification task revealed significant differences in category compactness between monolingual and bi/multilingual speakers. In addition, substantial variability in compactness exists across all groups, which suggests that compactness may be influenced by individual differences apart from the number of languages spoken.

The final article by Disney and Le examines the production of lexical and morphological word-final /s/ and /z/ by Vietnamese adult learners of English. Their study explored the impact of frequency of use, the nature of the morpheme (whether it is a root or bound morpheme), and the phonetic context of the preceding sound (whether it is a consonant or a vowel) through analysing production data obtained from participants’ individual oral presentations. A multilevel binary logistic regression revealed that morphological words containing /s/ or /z/ were significantly more likely to be pronounced with the /s/ or /z/ absent than lexical words containing a /s/ or /z/, as were those in clusters compared to those with a preceding vowel. Disney and Le argue that the results indicate that phonological effects and morphological effects are stacked and not multiplicative and that the observed omission rates are not solely attributable to L1 transfer effects. Moreover, the frequency of use also correlated strongly with accuracy.

While we believe that the selected papers helped us achieve some of the aims we outlined above, e.g., showcasing work from different geographic contexts involving participants from a range of linguistic backgrounds, we believe that there is still work to be carried out in strengthening the empirical bases for work in L2 phonetics and phonology. For example, given the current geo-socio-political climate, work pertaining to the acquisition and assessment of low literate and non-literate learners, many of whom are undergoing or have undergone forced migration, is so very much needed. Young-Scholten (2020) notes that almost none of the research encouraged by the establishment of ‘LESLLA’ (Literacy Education and Second Language Learning for Adults) in 2005 is on phonetics and phonology. Several decades ago, countries receiving immigrant adults with little or no native language schooling or literacy grappled with how to support their language and literacy development in a new language. To address these challenges, a group of researchers (including Special Issue co-editor Young-Scholten) established LESLLA (www.leslla.org, accessed on 1 December 2024) as a forum for the exchange of ideas and the promotion of research on this learner population. It is also important to understand the limitations under which such research is typically conducted. The challenges in locating, recruiting, and working ethically with these vulnerable participants should be acknowledged; therefore, research in this area should not be compared against studies based in laboratory or controlled experimental settings.

Work that pushes the boundaries of theory has long driven the formal study of language acquisition, as inspired by the paradigm-shifting ideas first proposed by (Chomsky, 1957), and laid down for the phonology of English by (Chomsky & Halle, 1968). Such theorisation in L2 phonology, especially across different linguistic domains, can provide framework that fuels further empirical investigations (see, e.g., Archibald, 2024a, 2024b). Related to that, there is also a need for investigations involving target languages that are less studied, which can, in turn, provide an expanded empirical base for the validation of previous findings as well as theory testing and verification. We hope that researchers interested in the study of L2 phonetics and phonology will continue to contribute to the expansion of this field from different theoretical and methodological perspectives.