An Investigation of the Phonetic Variation of the Word-Initial /l/ and /n/ Across Regional Varieties of Mandarin

This study investigates how word-initial /l/ and /n/ are phonetically realized in Mandarin Chinese as produced by speakers from three regions: Beijing (close to Standard Mandarin), Changsha (where Xiang, which contains /l/ but not /n/, is also spoken locally), and Meizhou (where Hakka, which contains both /l/ and /n/, is also spoken locally), focusing on acoustic cue use and phonological context effects. Using acoustic analysis and random forest classification, we analyzed five acoustic measures (F2–F1 spacing, F3 frequency, BW1, ΔA1, and A1–P0) and evaluated their contribution to distinguishing the two sounds. Results showed that speakers from different regions used distinct cue weighting strategies: Beijing Mandarin speakers relied more on spectral cues, Meizhou Mandarin speakers showed greater reliance on nasality-related cues, and Changsha Mandarin speakers combined both, with greater variability. Phonological context, including preceding nasals and following vowels, further modulated cue realization in region-specific ways. These findings demonstrate how native phonological background and phonological environment shape the phonetic implementation of a shared Mandarin contrast and illustrate the value of combining acoustic and classification-based approaches for modeling gradient phonetic variation.