Prelexical vocalization in normal hearing and hearing-impaired infants before and after cochlear implantation and its relation to early auditory skills

Objectives: To compare the vocalizations of hearing-impaired infants before and after cochlear implantation with those of a control group of hearing infants and to relate prelexical vocalizations by using the PRoduction Infant Scale Evaluation (PRISE) to early auditory skill attainments, using the Infant-Toddler Meaningful Auditory Integration Scale (IT-MAIS) in normal-hearing and hearing-impaired (HI) infants before and after cochlear implantation. Design: A total of 187 infants participated in the study: 24 HI infants with severe-profound hearing loss (8 to 23 months of age) and 163 hearing infants (0.5 to 20 months of age). Prelexical vocalizations and early auditory skills were assessed by using parent questionnaires (PRISE and IT-MAIS, respectively) that reflect known milestones in the infant's vocal and auditory development. HI infant data were compared with hearing infant data according to chronological age and duration of device use (hearing aid or cochlear implant). Results: Average PRISE score of aided HI infants before implantation was 50% or less (regardless of age). This score is comparable to that of hearing infants who are 6 to 7 months of age. After implantation, HI infants reached a score of 70% but did not reach normative performance. When HI infant data were compared with hearing infants by duration of device use, aided infants before implantation performed as well or worse than normative performance, whereas implanted infants performed as well as or better than hearing infants. Performance on individual PRISE questions showed limited ability by HI infants before implantation compared with hearing and implanted infants. A strong correlation was found between the IT-MAIS and the PRISE (r = 0.93 and r = 0.83, for hearing and HI infants, respectively). Conclusions: The PRISE was found to be a versatile tool for implant team clinicians who are required to assess prelinguistic skills of infants. The findings suggest that early auditory skills are related to prelexical vocalization. The data also highlighted unanswered questions related to the importance of early fitting of hearing aids on vocalization before and after implantation.