Perception and Production of Audiovisual Speech in Children with Hearing Loss
Nicholas Smith, PhD
The overall goal of this project was to evaluate how mothers modify their speech when addressing their children under conditions of reduced audibility, such as at various levels of background noise, and to test whether these speech modifications produce perceptual benefits in terms of increased speech intelligibility. Previous work on caregiver speech acoustics had focused primarily on speech to young infants as a means of promoting long-term speech and language development, and had not examined whether child-directed speech enhances the intelligibility of speech for children.
The project consisted of three aims. The first aim was to evaluate how mothers adapt their speech when communicating to children under difficult listening conditions. The second aim was to evaluate whether the mothers' speech adaptations are effective in increasing the intelligibility of speech to children. And finally, the third aim was to evaluate how children adapt their visual strategies in an audiovisual speech-perception task as a function of noise level and hearing loss.
These experiments indicate that mothers modify both the acoustical and visual components of their speech to children. For instance, they use a higher pitch and speak louder and slower when talking to their children than to another adult. The visual modifications consist of exaggerated facial movements related to their speech. This project demonstrated that both the acoustical and visual modifications in child-directed speech lead to increased speech intelligibility in conditions of background noise. These finding are important because they demonstrate that caregivers continue to modify their speech to children through early childhood in ways that support children's speech and language perception.