AN ULTRASOUND AND EPG INVESTIGATION OF CORONAL FRICATIVES IN YANBIAN KOREAN

This paper investigates the tongue gesture difference of the two-way coronal fricative contrast in Yanbian Korean through ultrasound imaging and electropalatography(EPG).Ultrasound imaging was applied to compare the mid-sagittal tongue contours of the fortis and non-fortis coronal fricatives.Results show that the two-way fricative contrast is distinguished by the positioning of tongue blade,anterior tongue body,and tongue root.The fortis fricative is characterized with higher tongue blade and anterior tongue body,and more fronted tongue root than the non-fortis fricative.However,this pattern is slightly blurred in the palatalized fricative contrast due to the interspeaker variability.Part of the variability may be attributed to the supra-glottal cavity enlargement when the nonfortis fricative is realized as voiced.The acoustic examination shows that the frication duration and the spectral center of gravity are two defining acoustic properties that contrast the two fricatives.Whether the non-fortis fricative is realized as voiced fricative tends to be affected by vocalic context and gender.The EPG results show that the defining articulatory property for the contrast is the medial constriction degree at the alveolar region.The inter-speaker variability is solely found in the posterior region,which corresponds to the variability in the positioning of the anterior tongue body in the ultrasound investigation.The emergence of the inter-speaker variability in the production of the fortis/non-fortis fricative contrast calls for a more comprehensive model for the production of the Korean coronal fricatives which should entail aerodynamic and sociolinguistic factors.