Phonetic differences between nouns and verbs in their typical syntactic positions in a tonal language: Evidence from disyllabic noun–verb ambiguous words in Standard Mandarin Chinese

This study investigates how word categories, namely noun and verb, influence acoustic realizations (duration, F0, intensity) in Standard Mandarin Chinese, a language having phonemically distinctive tones and a simple morphological system. Noun-verb ambiguous words were selected and presented in the final positions of typical syntactic contexts in order to avoid the interference of prosodic boundary, syntactic complexity, contextual predictability, tonal environment, F0 range and syllable properties (consonant, vowel, tone, syllable length). Linear mixed models were fitted to duration, and generative additive mixed models were fitted to F0 and intensity. The results showed that phonetic differences between nouns and verbs were still evident in duration, F0 and intensity after lexical frequency, speech rate and some other related factors were taken into consideration in the models. The second syllables of nouns were longer than those of verbs, and both syllables of nouns were higher in F0 and greater in intensity than those of verbs. Since the prosodic boundary, frequency and other factors were controlled for, the phonetic differences between nouns and verbs might be attributed to their differences in information load and number of syllables. This study provided evidence that phonetic differences between nouns and verbs might be driven by the grammatical classes themselves and is not an epiphenomenon of other processes.