The costs and benefits of providing early intervention to very young, severely hearing‐impaired children in the United States: The conceptual outline of a longitudinal research study and some preliminary findings

Abstract
This paper presents the conceptual framework for a newly instituted longitudinal research study into the costs and benefits of providing early intervention to very young, severely hearing-impaired children in the USA and the results of one of the studies after 2 years of intervention. The research design employs randomised procedures, blind assessment and treatment verification. The overall project is part of a 20 experiment national study that addresses specific questions about the effects of early intervention on the psychological development of hearing-impaired children. Those questions regard age-at-start, treatment intensity and programme variation. Two of the three experiments with hearing-impaired children are still in developmental stages, whilst the third, a communication methods comparison, has been started. The preliminary findings of the third experiment (which include 2 years of intervention effects) are presented. Two groups of young, severely hearing-impaired children between the ages of 18 months and 5 years (one an oral-aural group and one called an English sign language group) have received 20 months of intervention in one or other of the groups. Their developmental progress has been measured using the Battelle Developmental Inventory, several specific English language measures and two family measures. Whilst both groups showed significant progress over intervention time on all measures, the performance differences between the two groups were not statistically significant in any of the psychological domains tested.