Phonation types and stop consonant distinctions: Shanghai Chinese

In this study, acoustic, perceptual and physiological investigations on stop consonants in Shanghai Chinese have been carried out. It has been found that the major differences among the three categories of Shanghai stops lie in laryngeal control. Acoustically, voice onset following categories 2 and 3 has more energy in the first harmonic, suggesting that the glottis may be more abducted in these two categories. Perceptually, the spectral difference is a sufficient cue for distinguishing categories 1 and 2. A steeper spectral slope resulting from a relatively more prominent first harmonic elicits more category-2 responses. Fundamental frequency (F$\sb{\rm o})$ also contributes to the perception. A higher F$\sb{\rm o}$ onset results in more category-1 judgments. Physiologically, the airflow data show that at voice onset, categories 2 and 3 have greater values of open quotient of the glottal cycle, maximum airflow and minimum airflow than category 1. The transillumination data show that in the voicing domain, only category 2 has voicing during closure in medial position. There are also differences in laryngeal adjustment along both spatial and temporal dimensions among the three stop categories. As to the size of the glottal opening, the order is category 1 $<$ category 2 $<$ category 3. In the temporal dimension, there are differences in the timing of peak glottal opening relative to the release of the supraglottal closure and voice onset. These differences in laryngeal adjustments among the three categories determine not only whether and when the vocal folds vibrate, but also how they vibrate early in the vocalic stretch. In light of the data, three hypotheses are discussed. It is concluded that the three stop categories are mainly distinguished by phonation types. Category 1 is more adducted. Category 2 is more abducted. Category 3 is the most abducted. Further studies are suggested. ^