Communication is the most fundamental component of human interaction and learning. Sound production, perception, and understanding are prerequisite to spoken language learning, and, ultimately the attainment of higher level cognitive skills. The healthy neonate is prepared to begin the process of language development and can perceive sounds at birth, although responses such as the ability to localize to the direction of a sound source continue to mature during infancy. Assessment of hearing may be performed within hours after birth through behavioral observation by a trained examiner and by tests such as the auditory brainstem response or otoacoustic emissions.

Without intervention, hearing impairment has a calamitous effect on the speech and language development of a child. Impairment may also cause significant deficits in educational and psychosocial development. Even minimal, unilateral, and transient hearing loss from otitis media has been shown to have a detrimental impact (Bess, Dodd-Murphy, & Parker, 1998). Children who receive intervention for hearing loss within the first 6 months of life have significantly better language outcomes and improved overall development in a number of areas, compared with those who receive later intervention (Yoshinaga-Itano, 1998; Yoshinaga-Itano & Apuzzo, 1998).

Diagnosis and intervention must take place during the first year of life, ideally within the first 6 months. At present, the age of identification of hearing loss in the United States still averages 12 to 25 months, with an additional delay of up to 1 year prior to intervention. These averages are far from the U.S. Department of Health and Human Services’ Healthy People 2010 goal of increasing “to 100 percent the proportion of newborns who are screened for hearing loss by 1 month of age, have diagnostic follow-up by 3 months and are enrolled in appropriate intervention services by 6 months” (1999, section 12, objective 33). Delays in identification and intervention have been attributed to the following three factors:

Established screening programs have documented success in reducing the age of identification and intervention for hearing loss, and their performance improves with time. For example, the Rhode Island Hearing Assessment Program decreased its initial mean ages of confirmation (8.7 months) and intervention (13.3 months) to 3.5 months and 5.7 months respectively from 1993 to 1996 (Vohr, Carty, Moore, & Letourneau, 1998). Universal infant hearing screening programs, such as the Rhode Island initiative, are highly sensitive, specific, and cost effective.

Infant hearing screening is inexpensive compared with other forms of disease screening, with a cost ranging from about $10.00 to $30.00 per infant screened or about $5000.00 to $10,000.00 per hearing loss identified (Maxon, White, Behrens, & Vohr, 1995; Mehl & Thomson, 1998). The cost of screening plus intervention for those with hearing loss has been shown to compare favorably with the cost of special education and language services that would otherwise be required (Mehl & Thomson, 1998). Useful guidelines for infant hearing screening programs have been published by a task force of the American Academy of Pediatrics (Erenberg, Lemons, Sia, Trunkel, & Ziring, 1999). A model of a typical hospital-based infant hearing screening program can be found in Appendix 53-1.

Even when infants receive hospital-based hearing screening, there is always the possibility of a later onset or progressive hearing impairment. For these infants, parental concern is often the chief means of identification. Typically, such concerns are initially addressed with the child’s primary care provider. Therefore, the primary care provider forms a crucial link between children who have or are at risk for hearing loss and the wide range of services available to meet their needs. One of the objectives of the draft of Healthy People 2010 guidelines (1999) is to “increase the proportion of primary care providers who routinely refer or screen infants and children for impairments of vision, hearing, speech, and language… as part of well-child care” (U.S. Department of Health and Human Services, Section 12, objective 38). Early identification of hearing loss, frequent monitoring, appropriate medical and rehabilitative intervention, and realistic parental counseling continue to be the best means to reduce the devastating impact of hearing loss.

When an airborne sound wave enters the ear canal, it is amplified, filtered, and converted by the intricate structures of the auditory system from acoustic to mechanical to electrochemical energy and ultimately to neural impulses. These neural impulses are organized by their timing and place within the auditory system, from cochlea to auditory cortex. Understanding the anatomy and physiology of the auditory system is essential to understanding how its different sections are affected by pathologies.

The system is often divided into the peripheral (outer, middle, and inner ear) and central auditory systems. To facilitate the understanding of the interrelationship between anatomy, physiology, and pathology, the divisions that are used here are related to possible sites of lesions, including the following:

The reported prevalence rates of peripheral hearing loss among children are quite variable. These values depend both on age and on the type and severity of the hearing loss (ie, unilateral versus bilateral, conductive versus sensorineural).