Auditory development and hearing evaluation in children.

This chapter provides an overview of (1) developmental timetables relevant to hearing, and (2) current pediatric audiological techniques and practices. Structural and functional development of the auditory pathway and the development of primary auditory processing are summarized. These developmental sequences appear to follow similar paths in humans and animals. Speech and music perception involve more complex processing and are strongly influenced by experience. Hearing disorders affect the perception of complex sounds in a variety of ways, depending on the sites of lesions. Early-onset hearing impairment, including conductive loss from chronic otitis media, can seriously impede language development. Language cannot develop normally without adequate speech stimulation, and deafness is more prevalent than any other handicapping condition for which mandated neonatal screening programs exist. Sensitive and inexpensive techniques are available for performing neonatal hearing screening, and early intervention has a documented positive effect on development of language skills in hearing-impaired children. Thus, the National Institutes of Health has recommended nationwide universal neonatal hearing screening. The rationale for and the methodology of universal screening programs are summarized. Advances in the genetics of hearing impairment are reviewed. Data from these studies have influenced testing and rehabilitative protocols and have implications for future prevention and treatment of hearing impairment.