Prosody-modulated and vowel-dependent nasal merger in Taiwan Mandarin

While Taiwan Mandarin alveolar and velar nasal codas are reported to lose their place contrast in a vowel-dependent fashion (i.e., more pervasive merging in the /iN/ context, followed by the /əN/ context, and no merging in the /aN/ context), other acoustic cues, such as vowel nasalization, have been reported to preserve the contrast. Results from our ultrasound experiment, in which Taiwan Mandarin speakers produced nasal codas in both focused and unfocused conditions, showed that the place contrast was most vulnerable to merger in /iN/ and /əN/ contexts and was not enhanced by focus. Instead, pre-nasal vowel nasalization emerged as a contrastive cue, especially in the highly merged /iN/ context in both focus conditions, suggesting a possible shift from place contrast to nasality contrast in production. A follow-up identification experiment revealed that speakers did not yet utilize the nasalization cues reliably to perceptually identify nasal codas, indicating a mismatch in the perception-production link.