A Study On The Phonation Characteristics In Mandarin Prosody

The purpose of this study is to investigate the phonation characteristics of Mandarin prosody. So far, only the acoustic features of F0, time duration and amplitude have received much attention in a majority of studies on Mandarin prosody, but very little has been done on its phonation characteristics. This study is theoretically based on the source-filter theory of speech production, according to which the main features of language prosody are characterized at a phonation level. To begin with, we conduct some preliminary studies on the acoustical and physiological methods of voice assessment, as well as on the acoustical and physiological mechanisms of the voice production. On the basis of these, we discuss the mechanisms of pitch, length, loudness controls and the interrelationship between them, which make up the primary features of language prosody.We use EGG(electroglottography) as the main method of voice assessment, and discuss the application and interpretation of EGG signals. Drawing on the former literature on EGG analysis, we use a 25% criterion level algorithm for EGG analysis, by which we extract the voice parameters of F0, OQ(Open Quotient) and SQ(Speech Quotient), etc. It is also discussed that the acoustic correlations of OQ variation are mainly realized as spectral tilt variation, and those of SQ variation are closely related to spectral amplitude of the higher frequency region. For the acoustic analysis of spectral tilt and spectral amplitude of the higher frequency region, the intensity parameter with high frequency pre-emphasis(SPLH-SPL) and the Ee parameter of LF model are measured.An analysis study is conducted to observe the phonation characteristics of the reading corpus of Chinese modern style poetry. The results of linear regression analysis show that the overall phonation characteristic is realized as a linear feature; the regression function between F0 and OQ is a plus correlation, but that of between F0 and SQ is a minus correlation. An advanced nonlinear statistical analysis finds two breakpoints each at a high and low F0 region, which indicate the occurrence of transition between various phonation types. Our EGG analysis classifies those phonation types into a feature matrix, and then we discuss how four Mandarin tones can be characterized by the combination and transition between those phonation types. We also find out that language prosody affects a number of exceptional cases, which are not consistent with the overall phonation characteristics. For one of the main rhythmic features of Mandarin prosody, we investigate the phonation characteristics of respiration rhythm. The results of EGG and acoustic analysis show that, on the boundary of respiration units, F0 is lowered, but OQ increases, SQ decreases, as well as the acoustic parameter of SPLH-SPL decreases, which is realized as the lowered spectral amplitude in higher frequency region. These characteristics reflect the physiological restriction of respiration rhythm, which is that the subglottal pressure and glottal tension is lowered on the boundary of the respiration units.As for one of the melodic features of Mandarin prosody, we conduct an experimental study on the phonation characteristics of sentence focus. The results show that there are obvious sex differences at the high tone region. The focused syllables of the female voice are characterized by F0 rising, OQ increasing and SQ decreasing, which is consistent with the basic characteristics of weak falsetto phonation. But those of the male voice are characterized by SQ increasing, which is related to the raised spectral amplitude in the higher frequency region. The result of linear regression analysis between Ee parameter and intensity shows that the male voice needs more spectral amplitude of the higher frequency region than the female voice. This means that the male voice increases the amplitude of the higher frequency region, but the female voice increases that of the lower frequency region; at the low tone region, focused syllables of both male and female voices are characterized by slightly lowered FO and increased SQ, which is consistent with the main features of creaky voice. Although FO variation is not a big margin, the increased spectral amplitude of the higher frequency region is the significant feature of low tone focus.This study concerns itself with the physiological and acoustical features of the phonation characteristics of respiration rhythm and sentence focus, which is a significant element each to the rhythmic and melodic prosody of Mandarin. We find that these prosody features are realized as obvious variations in phonation characteristics, and these findings provide us the groundwork for an in-depth understanding of Mandarin prosody. On the basis of this study, we need to explore a number of elements of Mandarin prosody and their phonation characteristics. Moreover, further research should also be directed at investigating the role of phonation characteristics to the perception of Mandarin prosody, since they are closely related to the perception of language prosody.