In noisy situations, talkers adapt the way they speak to be more intelligible. Similarly, listeners adapt their processing strategies by increasing their reliance on visual information on the talker's face to compensate for the degraded auditory information. The goal of this research program is to understand the process of reciprocal adaptation in speech production and perception between mothers and their preschool children. In Aim 1, we will examine how mothers adapt the visual and acoustical properties of their speech when talking to children with hearing loss and children with normal hearing under conditions of background noise. By simultaneously tracking mothers' speech related head movements while analyzing their speech acoustics, we can assess the ways in which mothers might exaggerate their speech to make it more intelligible to their children. In Aim 2, we will directly test whether speech directed to children with hearing loss, or produced in the presence of high levels of background noise, is more intelligible to children in a speech-recognition task. These measurements will be made in an auditory-only mode, without visual information. In Aim 3, we will use eye tracking to examine children's visual processing of videos of their mothers' speech to test the degree to which visual information enhances speech recognition, how background noise affects children's attention to talker facial regions, and whether visual fixation on the mother's mouth increases speech intelligibility. One important way of implementing successful interventions for children with hearing loss involves coaching parents to provide language input that facilitates speech and language development. By understanding the reciprocal adaptations that occur in the production and perception of mother-child speech, and how they are impacted by hearing loss, this project will provide an empirical basis for the identification and implementation of clinical intervention practices for audiovisual speech perception problems in children, and improve the developmental outcomes for children with hearing loss.