The quantification of place of articulation assimilation in electropalatographic data using the similarity index (SI)

The present study is concerned with an electropalatographic (EPG) and acoustic analysis of coarticulatory influences in fricative consonant clusters that span a word boundary. We aimed to test whether, as has been found for other languages and consonant-classes, final consonants are more prone to coarticulatory influences than initial ones, and also whether there is any evidence for a relationship between a consonant's susceptibility to coarticulation and the extent to which it exerts a coarticulatory influence on flanking consonants. We developed an algorithm, the similarity index (SI), which quantifies coarticulation in EPG data by measuring the extent of deviation of consonants in heterorganic clusters from their homorganic counterparts. This algorithm was applied to EPG data recorded from three native speakers of Polish producing word-pairs in a carrier sentence such that word-final and word-initial fricatives occurred across a word-boundary for all 16 possible combinations of the four fricatives image omitted]]. The same data were analysed acoustically using Bark-scaled cepstral coefficients. The results showed that word-final consonants were more susceptible to coarticulatory influences than were initial ones; and there was some evidence that the alveolopalatal fricative image omitted]] was most resistant to coarticulation, and exerted the greatest coarticulatory influences.