By definition, behavioral audiometry is a screening test used in infants to observe their behavior in response to certain sounds. The purpose of this test is to assess the hearing acuity in infants and young children.
Behavioral audiometry in young children observes the changes in their behavior when exposed to an acoustic stimulus from speakers or with Hear-Kit Noisemakers. The test establishes the child's range of hearing and can determine the degree of hearing loss, if any.
An audiogram can be used to determine the softest sounds a person can hear at various frequencies. This hearing threshold is determined by the lowest intensity (dB HL) at which a frequency specific tone can be detected. The threshold should be detectable 50% of the time. Normal hearing is defined as having a threshold of at least 15dB HL.
Audiologists use two types of methods to determine hearing loss. They are air conduction which uses headphones or speakers to deliver sounds and bone conduction which uses a bone vibrator placed on the mastoid bone to deliver sounds to the inner ear. Comparing the two results helps the audiologist determine whether the hearing loss is conductive, sensorineural or a mixture of the two.
The child's age and developmental level will determine the method of testing. In the case of infants and toddlers younger than six months, exposure to the test sounds will cause them to turn their heads. For children between the ages of 6 months to about three years, VRA is the behavioral test of choice. The test is carried out in a soundproof room and the child is trained to look at something which will hold their attention, like a toy or a puppet, on hearing a sound. The child sits in the caregivers lap. Sounds are introduced via a speaker or earphones.
On hearing the sound, the child will turn towards the sound and is rewarded with something which makes the child happy. The procedure continues with a series of entertaining videos that keep the child engaged while determining the threshold values of different sound frequencies.
VRA is not usually used in the case of children over the age of two and a half years. Older children are asked to carry out some simple tasks such as dropping a brick, or closing a door when they hear a sound. . This procedure is known as a conditioned play audiometry (CPA). Children over the age of 4 are asked to respond by raising their hands or pressing a buzzer.
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