Coarticulatory Aggression and Direction of Coarticulation:An Ultrasound Study

Coarticulatory pattern can be varied based on the articulatory dynamics of the sound produced. The present study aims to analyze some of the coarticulatory patterns such as coarticulatory aggression and direction of coarticulation based on ultrasound imaging technique. Ten adult Kannada speakers participated as subjects. The stimuli consisted of V1CV2 sequences, with C corresponding to voiced/voiceless counterparts of dental stops (/t̪/, /d̪/) or retroflex stops (/ʈ/, /ɖ/) or velar stops (/k/, /g/), in the context of vowels /a, i, u/. Measurements of coarticulation resistance of consonants were carried out based on Root Mean Square (RMS) distance between the tongue contours of consonant and vowel. Results showed that there was a clear pattern of minimum extent of coarticulation from intervocalic consonant to following vowel in VCV syllable structure. Significant coarticulatory aggressive was noticed in high front vowel /i/ at all three places of articulation considered. Anticipatory coarticulation was evident across dental, retroflex, and velar stop consonants. Overall, the study agreed that the pattern of coarticulation explained using Degree of Articulatory Constriction (DAC) model and the duration of phoneme planning varied as a property of articulatory dynamics.