A Phonetic Study of Syllable-initial /n/ and /l/ in Standard Mandarin

In Standard Mandarin, the syllable-initial /n/ and /l/ are distinguished as separate phonemes. This study examines the phonetic differences between /n/ and /l/ in various vowel contexts by analyzing their articulatory, acoustic, and aerodynamic properties. Ultrasound imaging, oral and nasal airflow data, and acoustic recordings were collected from eight native speakers. In terms of articulation, /n/ and /l/ share similar tongue shape and tongue position, and their major difference lies in the tongue body posture. Compared to /n/, /l/ shows a larger variation in tongue body posture across different vowel contexts. Aerodynamically, /n/ consistently displays a higher consonantal nasal ratio (NR), while /l/ tends to induce an increased NR before the high front vowel /i/. A compensatory pattern emerges between consonantal nasal ratio and vocalic nasal ratio, helping preserve the /n/-/l/ distinction. Acoustically, the main difference lies in the distribution of spectral energy, while their formant patterns remain comparable. The experimental data obtained in this study reveal the differences between /n/ and /l/, which contribute to the perceptual distinctiveness between the two coronal consonants in Standard Mandarin.