Auditory Steady State Response (ASSR)
Auditory Steady State Response (ASSR) is an objective test used for evaluation of hearing ability in children too young for traditional audiometric testing. Most children are referred for ASSR after a newborn hearing screen in the hospital indicates the possibility of hearing loss. Early intervention strategies, such as hearing devices or cochlear implantation, are necessary for development of speech and language skills in a child with hearing impairment. The results obtained from ASSR testing can be used to estimate the behavioral pure-tone audiogram. This information is essential in the management of children with hearing loss.
The person being tested must be very quiet and still in order to obtain reliable ASSR results. Often, testing is performed under sedation or in natural sleep if the person is under 6 months of age. Results are obtained by measuring brain activity while the person listens to tones of varying frequency (pitch) and intensity (loudness).
The brain activity is recorded using electrodes taped on the forehead and behind each ear. The use of electrodes eliminates the need for active participation of the patient (i.e., pushing a response button every time a tone is activated). The results are detected objectively using statistical formulas that determine the presence or absence of a true response. Similar to traditional audiometric testing, threshold is determined as the lowest level at each frequency at which a response is present. ASSR provides an accurate, frequency-specific estimate of the behavioral pure-tone audiogram.
The use of ASSR in estimating hearing loss in children was the subject of a recent study by Audiologists at California Ear Institute. The article “Estimation of Hearing Loss in Children: Comparison of Auditory Steady-State Response, Auditory Brainstem Response, and Behavioral Test Methods” was published in the American Journal of Audiology in December 2003.