# Near-Merger and Contextual Sensitivity in the Perception of /n-l/ in Sichuan Mandarin

## TL;DR

This study explores how Sichuan Mandarin speakers perceive the /n-l/ sound contrast, finding that it depends on vowel context and available acoustic cues.

## Contribution

The study introduces a context-dependent near-merger model of /n-l/ perception in Sichuan Mandarin, driven by vowel-specific acoustic cues.

## Key findings

- Perceptual separation of /n-l/ is stronger in /i/ contexts compared to /a/ contexts.
- Vowel-dependent acoustic cue structure, not decision bias, drives the asymmetry in perception.
- Age, education, and Mandarin experience affect response efficiency but not the vowel context asymmetry.

## Abstract

What was done?
Sichuan Mandarin listeners’ perception of the /n-l/ contrast was examined using graded acoustic continua in different vowel contexts.Signal-detection and mixed-effects modeling were used to separate sensitivity, bias, and contextual cue effects.

Sichuan Mandarin listeners’ perception of the /n-l/ contrast was examined using graded acoustic continua in different vowel contexts.

Signal-detection and mixed-effects modeling were used to separate sensitivity, bias, and contextual cue effects.

What was found?
The /n-l/ contrast patterns as a context-dependent near-merger, with substantially greater perceptual separation in /i/ than in /a/.Vowel-dependent acoustic cue structure, rather than decision bias, drives this asymmetry, showing how contrast representations depend on available phonetic evidence.

The /n-l/ contrast patterns as a context-dependent near-merger, with substantially greater perceptual separation in /i/ than in /a/.

Vowel-dependent acoustic cue structure, rather than decision bias, drives this asymmetry, showing how contrast representations depend on available phonetic evidence.

Background/Objectives: Sichuan Mandarin is often described as exhibiting overlap or merger between word-initial /n/ and /l/, but perceptual sensitivity across phonetic contexts remains underexplored. This study examines whether perception of the /n-l/ contrast varies by vowel context and listener experience. Methods: Thirty-two Sichuan Mandarin listeners completed categorical identification and same–different AX discrimination tasks using seven-step /n/ → /l/ continua derived from native-speaker productions in /i/ and /a/ contexts. Sensitivity, response bias, accuracy, and response times were analyzed alongside individual differences. Acoustic properties of the stimuli were quantified using spectral and amplitude-based measures. Results: Listeners showed overall reduced sensitivity to the /n-l/ contrast, with substantially stronger perceptual differentiation in /i/ than in /a/ contexts. Bias patterns were comparable across contexts, indicating sensitivity-driven effects. Acoustic analyses showed more robust cue structure in the /i/ continuum. Age, education, and Standard Mandarin experience modulated response efficiency but did not eliminate the vowel asymmetry. Conclusions: Results support a context-dependent near-merger of /n/ and /l/, shaped by acoustic cue availability and experience-based cue exploitation.