While deafness in early childhood leaves permanent changes in how sounds are processed in the brain, researchers found that even mild-to-moderate hearing loss have a similar impact. Researchers say that the findings may have implications for how babies are screened for hearing loss and how mild-to-moderate hearing loss in children is managed by healthcare providers. The structure and function of the auditory system, which processes sounds in the brain, develops throughout childhood in response to exposure to sounds. In profoundly deaf children, the auditory system undergoes a functional reorganisation, repurposing itself to respond more to visual stimuli, for example. However, the brain responses of older children with hearing loss were smaller than those of their normally hearing peers. To confirm these findings, the researchers re-tested a subset of the group of younger children from the original study, six years later. In the follow-up study, the researchers confirmed that as the children with hearing loss grew older, their brain responses changed. Responses that were present when the children were younger had either disappeared or grown smaller by the time the children were older. There was no evidence that the children's hearing loss had worsened over this time, suggesting instead that a functional reorganisation was occurring.