This thesis examines the neurodevelopment of two under-studied cohorts of children who are at risk of hearing and communication problems. Assessment methods included clinical and experimental tests of auditory function, speech discrimination and psychoacoustics evaluation, and the use of parental questionnaires. Advanced MRI methods were used to examine the effects of the two conditions on neurodevelopment and brain microstructure. The first group of children had all been diagnosed with auditory neuropathy spectrum disorder (ANSD). Difficulties with speech discrimination were seen in the ANSD group as expected, and associations were found with temporal processing abilities as well as with brain MRI measures. Children from the second group were diagnosed with congenital hypothyroidism (CH) through the Newborn Bloodspot Screening Programme. In the CH group, hearing and communication problems were found for some children along with evidence of structural white matter abnormalities in the brain and associations between white matter microstructure and hearing abilities. This thesis shows that children with ANSD and children with CH have variable outcomes for hearing and communication and provides evidence that advanced MRI methods can support our understanding of the development of children with these conditions.