Outcomes of Children with Hearing Loss: Data Collection and Methods

The primary objective of this article was to describe recruitment, data collection, and methods for a longitudinal, multicenter study involving children with bilateral mild to severe hearing loss. The goals of this research program were to characterize the developmental outcomes of children with mild to severe bilateral hearing loss during infancy and the preschool years. Furthermore, the researchers examined how these outcomes were associated with the child's hearing loss and how home background and clinical interventions mediated and moderated these outcomes.

The participants in this study were children who are hard of hearing (CHH) and children with normal hearing (CNH) who provided comparison data. CHH were eligible for participation if (1) their chronological age was between 6 months and 7 years of age at the time of recruitment, (2) they had a better-ear pure-tone average of 25 to 75 dB HL, (3) they had not received a cochlear implant, (4) they were from homes where English was the primary language, and (5) they did not demonstrate significant cognitive or motor delays. Across the time span of recruitment, 430 parents of potential children with hearing loss made contact with the research group. This resulted in 317 CHH who qualified for enrollment. In addition, 117 CNH qualified for enrollment. An accelerated longitudinal design was used, in which multiple age cohorts were followed long enough to provide overlap. Specifically, children were recruited and enrolled continuously across an age span of 6.5 years and were followed for at least 3 years. This design allowed for tests of time (period) versus cohort age effects that could arise by changes in services and technology over time, yet still allowed for examination of important developmental relationships.

The distribution of degree of hearing loss for the CHH showed that the majority of CHH had moderate or moderate-to-severe hearing losses, indicating that the sample undersampled children with mild HL. For mothers of both CHH and CNH, the distribution of maternal education level showed that few mothers lacked at least a high school education and a slight majority had completed a bachelor's degree, suggesting that this sample of research volunteers was more advantaged than the United States population. The test battery consisted of a variety of measures concerning participants' hearing and behavioral development. These data were gathered in sessions during which the child was examined by an audiologist and a speech-language examiner. In addition, questionnaires concerning the child's behavior and development were completed by the parents.

The Outcomes of Children with Hearing Loss study was intended to examine the relationship between variation in hearing ability across children with normal and mild to severe hearing loss and variation in their outcomes across several domains of development. In addition, the research team sought to document important mediators and moderators that act between the hearing loss and the outcomes. Because the study design provided for the examination of outcomes throughout infancy and early childhood, it was necessary to employ a number of different measures of the same construct to accommodate changes in developmental performance across age. This resulted in a large matrix of measures across variable types and developmental levels, as described in this manuscript.