Lingua-palatal coarticulation by deaf and normal-hearing speakers

Recent research suggests that deaf speakers often exhibit context-dependent changes in speech articulation [for example, Mahshie etal., ASHA 32 (10), 183 (1990)]. However the coarticulatory patterns of deaf speakers are not always comparable to those of normal-hearing speakers. Furthermore, it is likely that deaf individuals exhibit differences among themselves in both the nature and extent of coarticulation–differences that may affect intelligibility. The purpose of the present study was to examine and compare lingua-palatal coarticulation evidenced by normal-hearing speakers and by deaf speakers differing in overall speech intelligibility. Three normal-hearing subjects, one intelligible deaf subject, and one semi-intelligible deaf subject produced multiple iterations of bisyllabic and trisyllabic words. Test words contained the lingua-alveolar target segments /t/ or /n/ followed by either the neutral vowel /schwa/ (e.g., ‘‘tana’’) or the velar consonant /k/ (e.g., ‘‘tancat’’). Palatometric measures were used to compare lingua-palatal contact patterns during production of the target consonants in the vowel and consonant contexts. Results showed that the intelligible deaf speaker, like the three normal-hearing subjects, exhibited context-dependent changes in articulation of the target segments, while the semi-intelligible deaf subject showed little evidence of anticipatory coarticulation. Possible motor organization strategies employed by the deaf subjects will be discussed.