AN ACOUSTIC MODELING STUDY OF FRICATION LEVELS OF HIGH VOWELS IN CHINESE

Frication of high vowels has three levels in auditory impression,including non-frication,low frication,and high frication.The aim of this study was to study the acoustic characteristics and social variability of the three levels via the method of multivariate statistical modeling.We estimated the weighting of each parameter by fitting the model of Boosted Logistic Regression to obtain the optimal parametric set.Pattern recognition then quantified the social variability with the optimal set.It showed that the acoustic characteristics of the vowel frication are mainly reflected in the formants,of which the second bandwidth (B2) plays the most prominent role in distinguishing the three levels.Three dimensional diagrams further illustrated that the high frication group has the greatest B2 value,with the smallest first formant (F1) and skewness,while the non-frication group is completely the opposite.Results of pattern recognition showed that the degrees of variation in age and gender are both close to 19%,where the higher the frication level is,the greater the variability is.This paper thus suggested that low frication variants should be treated as fricative approximants,instead of fricative vowels as reported in the literature.