Quality and quantity of infant-directed speech by maternal caregivers predicts later speech-language outcomes in children with cochlear implants

Caregivers speaking to children often adjust segmental and suprasegmental qualities of their speech relative to adult-directed (AD) speech. The quality and quantity of infant-directed (ID) speech has been shown to support word learning and word segmentation by normal-hearing infants, but the extent to which children with cochlear implants (CIs) benefit linguistically from ID speech is unclear. The present study investigated the extent to which the quantity and quality of ID speech produced in the lab by each of 40 mothers to her child with a CI predicted the child’s speech-language outcome measures at two years post-implantation. Multiple measures of ID and AD speech for each mother were taken, including ID speech quantity in one minute, and several measures of ID speech quality, including fundamental frequency characteristics, speech rate, and the area of the vowel triangle formed by corner vowels in F1-F2 space. Forward stepwise regression showed that both quantity and quality of speech significantly predicted language outcomes measured by the Preschool Language Scales, Peabody Picture Vocabulary Test, and the Reynell Developmental Language Scales. These results support the hypothesis that hearing more ID speech that has acoustic modifications typical of IDS promotes language proficiency in children with CIs.