This paper describes a pilot study that investigated the effects of auditory feedback on vowel production in prelingually hearing-impaired subjects. The rounding feature in French vowels is used to study the effects of hearing state on labial configurations and acoustic patterns. Subjects were recorded in two conditions: without their hearing aid (no auditory feedback) and with their hearing aid (with auditory feedback). The results show that temporary deprivation of auditory feedback causes changes in vowel production in the labial space. However, these changes are not reflected by a variation in vowel contrast, even though subjects tend to speak more clearly without their aid. It may be hypothesized that prelingually hearing-impaired subjects produce robust rounding features minimally influenced by temporary deprivation of auditory feedback.