The impact of prominence on CV coarticulation

The paper evaluates the quantitative impact of prominence (neutral vs emphatic stress) in CV sequences. The study serves the practical needs of speech synthesis and recognition and attempts to fill an important gap as there is insufficient research in the field with regard to the Russian language. We used the locus equation method to assess the degree of CV coarticulation. The experiment was performed on CVCV nonsense words imbedded in the middle position of a carrier phrase. The first syllable of the target words was made prominent both with neutral and emphatic stress. The consonants and vowels were presented by the same consonant and vowel sounds. Russian voiced occlusive bilabial, forelingual and backlingual consonants [b], [d] and [g] were combined with Russian non-palatal vowels [e], [a] and [u] occupying cardinal positions in the Fant triangle. Six male speakers were recorded in a sound attenuated studio using high-quality recording equipment. The total number of tokens N = 486. Praat software was used to measure formant frequencies by means of fast Fourier transformation and linear predictive coding. The experiment showed that linear regression slopes differed both in the Y-intercepts and slope coefficients for the vowels uttered with emphatic and neutral stress. We compared locus equation slopes for CV transitions of the consonants of similar place of obstruction combined with the vowels pronounced with neutral and emphatic stress, which revealed a quantitative difference in the degree of coarticulation of the bilabial and forelingual consonants both in the Y-intercept values and slope coefficients. In case of the backlingual consonant, locus equations differed only in the Y-intercept value, while the slope coefficients were practically the same. The results obtained were interpreted on the basis of existing experimental data for the Russian, English, and Arabic languages.