In the past 20 years, the prospects for hearing-impaired infants have improved significantly. It is now possible to diagnose deafness even in neonates and premature infants and to provide care that can prevent or ameliorate some of the most devastating effects of hearing loss. There have been steady advances in surgical and other medical procedures and in habilitation techniques. The value of many forms of therapy, however, depends greatly on how early intervention occurs.
Approximately one in 1,000, or 0.1%, of all infants are severely to profoundly deaf; their problems are permanent and pervasive. An estimated four to ten times as many infants suffer from hearing loss that is either unilateral or less than profound.
Hearing deficits affect language acquisition and consequently cognitive, social, and emotional growth. Behavioral and biologic evidence points to a critical time for linguistic development. Children normally master the language they hear around them by the age of 4 or 5 years, when they become competent to comprehend and produce all the variations of sentence construction found in adult speech. In this same period, deaf children can be taught sign language. The aptitude and flexibility for language acquisition diminishs with age. Early language deprivation results in permanent impairment.
Infants suspected of having hearing loss can be evaluated by means of auditory-evoked potentials, recently developed technology available at audiologic facilities throughout the country.