Effects of lexical difficulty on vowel production in adults with cochlear implants and normal hearing

Lexical difficulty impacts vowel production in adults with normal hearing. Specifically, adults with normal hearing hyperarticulate vowels in lexically hard words relative to lexically easy words. For adult cochlear implant users, auditory deprivation and subsequent exposure to a degraded auditory signal may modify phonological representations, potentially altering lexically conditioned phonetic variation. The objective of the current study was to compare vowel production in lexically hard and easy words in adults with cochlear implants and normal hearing peers. Participants read isolated monosyllabic words that varied in lexical difficulty, and vowel dispersion was calculated to assess vowel production differences based on lexical difficulty and hearing status. Results revealed that cochlear implant users and their normal hearing peers hyperarticulated vowels in hard words relative to easy words, consistent with previous studies. However, no differences in vowel production between the normal hearing and cochlear implant talkers based on lexical difficulty were found, although overall differences in the production of /i/ and /ɪ/ were observed between the two hearing groups. These findings demonstrate that adult cochlear implant users exhibit vowel production patterns comparable to those of normal hearing adults, potentially reflecting similarities in phonological representations across hearing groups.