Anticipatory coarticulation in dyads

Speech can be synthesized by concatenating dyads representing the transition between phoneme pairs. The resulting speech should be well coarticulated if the dyads themselves are free of coarticulatory influences and are therefore independent of context. We tested dyads for anticipatory coarticulation in 151 words as follows. Within each word, the /XæY/ sequence, where /X/ and /Y/ were consonants. were dyadically synthesized. The word /pæn/, for example, was synthesized with the dyads /pæ/ and /æn/. The /pæ/ dyad was an archetypal form derived from many words (pan, papoose, pad, sphagnum, etc.); the /æn/ dyad was taken unchanged from /pæn/. Only the segmental features were synthesized; the prosodic features were left intact. Listeners noticed degradation in words where anticipatory coarticulation of a nasal /Y/ consonant caused /æ/ to be nasalized: words with non-nasal /Y/ were well synthesized. We conclude that nasalized vowels are needed in dyadic synthesis to cope with anticipatory coarticulation of nasal consonants.