Auditory brainstem response
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Auditory brainstem response (ABR) is an electrical signal evoked from the brainstem of a human or other mammal by the presentation of a sound such as a click.
Auditory brainstem response audiometry is a screening test to monitor for hearing loss or deafness, especially notable for its use with newborn infants. It is a method employed to assess the functions of the ears, cranial nerves, and various brain functions of the lower part of the auditory system, prior to the child developing to the point of describing a possible hearing problem.
ABR audiometry is a safe and painless test of auditory pathway and brainstem function in response to auditory or (click) stimuli. The procedure was first described by Jewett and Williston in 1971. ABR audiometry is the most common application of auditory evoked responses. Test administration and interpretation are typically performed by an audiologist. (See reference)
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[edit] Infant hearing testing
ABR technology has been used in testing newborns for the past 15 years. Approximately 1 of every 1000 children is born deaf.[citation needed] Many more are born with less severe degrees of hearing impairment, while others may acquire hearing loss during early childhood.
Historically, only infants who met one or more criteria on the high-risk register were tested. Universal hearing screening has been recommended[citation needed] because about 50% of the infants later identified with hearing loss are not tested when neonatal hearing screening is restricted to high-risk groups. Recently, hospitals across the United States have been implementing universal newborn hearing screening programs. These programs are possible because of the combination of technological advances in ABR and otoacoustic emissions (OAE) testing methods and equipment availability, which enables accurate and cost-effective evaluation of hearing in newborns.
Moreover, the auditory brainstem response can also be measured in response to a complex speech signal. A growing body of literature has evaluated speech-evoked brainstem response differences between normal children and children with learning problems indicates that brainstem measures relating to the encoding of linguistic information can serve as a biological marker for auditory function in children with language-based learning problems, such as dyslexia. A consistent finding is that about one third of children with language-based learning problems exhibit a unique pattern of auditory neural activity that easily distinguishes them from the larger population of children with learning problems.
[edit] References
- Emedicine article on Auditory Brainstem Response Audiometry
- BIOMap: Biological Marker of Auditory Processing
