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Methods for Newborn Hearing Screening
Three screening strategies currently suitable for infant hearing screening were identified by an expert panel convened by the National Institute on Deafness and Other Communication Disorders (NIDCD) on September 4 and 5, 1997. These strategies use two of the current methods that have demonstrated to be effective for universal newborn hearing screening, namely auditory brainstem responses (ABR) and forms of otoacoustic emissions (OAE) testing. The newborn hearing screening methods recommended by the panel are: 1). ABR; 2.) OAE; or 3.) a combination of ABR and OAE.
As a result of this workshop, the panel made recommendations on Early Identification of Hearing Impairment on Acceptable Protocols for Use in State-Wide Universal Newborn Hearing Screening Programs.
The meeting occurred as a direct result of a recent collaboration between the NIDCD and two other agencies in the Department of Health and Human Services: The Maternal and Child Health Bureau (MCHB) and the Centers for Disease Control and Prevention (CDC). Representatives from the involved agencies previously met and agreed that sufficient research has been accomplished for universal newborn hearing screening to be implemented on a nationwide basis. The ultimate goal for the agencies is the successful screening of 85 percent or more of all newborns.
The Need for Early Identification of Hearing Impairment
As many as 12,000 infants are born each year in the United States with hearing impairment. The inability of the majority of these children to hear normally will go undetected until sometime after their second birthday. This late detection means that crucial years of stimulating the hearing centers of the brain will have been lost. The maturation and development of the hearing mechanism may be affected. Speech and language development will not begin. Social and emotional development may be retarded. And future success in school could be threatened. Additionally, some of these children may incorrectly be branded as difficult or intellectually inferior, simply because they have an undetected hearing impairment.
Early Attempts at Newborn Hearing Screening
The goal of detecting hearing impairment at birth has existed for decades. At first, only those infants classified as "high-risk" or who had conditions such as low birth weight, a family history of hearing problems, or other specific medical conditions were tested at birth by various methods which were often crude and inaccurate. Technology advanced, however, now allowing for more precise assessment of hearing at birth.
Recommended Methods for Newborn Hearing Screening
Auditory brainstem responses are measured by placing three electrodes on the baby's head or on the head and upper body. Sound is introduced to the baby's ears through tiny earphones while the child sleeps. The electrodes then measure if the brain is detecting the sounds. The test is painless and takes approximately five minutes to administer to a quiet, cooperative baby.
Otoacoustic emissions are faint sounds that are produced by most normal inner ears. These sounds are not heard by individuals but can be detected by very sensitive microphones placed in the ear canal. During otoacoustic emissions testing a tiny flexible plug is inserted into the baby's ear. Sound is then projected into the ear through the plug. A microphone inside the plug records the otoacoustic emissions that the normal ear produces in response to the incoming sound. The emissions are not detected in an infant who can not hear. Like ABR testing, this test is painless, takes only minutes to administer and is conducted while the baby sleeps.
The panel further recommended that the first hearing screening be carried out before three months of age to ensure that treatment can begin before six months of age. This is considered a period crucial for the initiation of speech and language development. The early identification process also requires more in-depth testing following identification. Counseling, treatment and parental educational programs are equally important. The panel stated that the entire process can best be achieved through a team approach. That team may include, but is not limited to, primary health care providers (physicians and nurses), neonatologists (physicians treating newborns), audiologists, otolaryngologists, educators, speech-language pathologists, and parents. The panel acknowledged that while the skill and commitment of the examiner influence the screening, studies have shown that the screening can effectively be carried out by a wide variety of personnel , such as nurses or volunteers, who have been appropriately trained.
The working group panel also strongly recommended that children continue to be monitored for hearing impairment and that all children have their hearing screened upon entering school as well as periodically thereafter.