An Ultrasound Study of Coarticulatory Resistance and Coarticulatory Aggression

Abstract

The term 'coarticulatory resistance' refers to the degree to which a given segment, a consonant or a vowel, resists potential interference of neighbouring segments. The phoneme has coarticulatory resistance exert stronger influence on neighbouring phoneme and exhibit less contextual variation, this characteristic termed as 'coarticulatory aggression'. The present study aims to analyse the coarticulatory resistance and coarticulatory aggression based on ultrasound imaging technique. Thirty adult Malayalam speakers participated as subjects. The stimuli consisted of VCV 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, preceding vowels and following vowels were carried out based on Root Mean Square (RMS) distance between the tongue contours of vowels and consonants. Results showed that coarticulatory resistance of consonants were decreased in the order from retroflex followed by velars and dentals. High front vowel /i/ resisted coarticulation of preceding consonant better than other vowels considered. It highlights the trend of Degree of Articulatory Constraint (DAC) model for both consonant and vowel system.