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.