What to expect when my child comes for a hearing test
A diagnostic hearing test is performed by a paediatric audiologist. The audiologist will perform a series of tests to determine if a hearing loss exists and if so, the type, degree and configuration of the hearing loss.
The following form part of the test battery:
Case history documentation
The audiologist will collect information about family history of hearing loss, conditions that occurred during pregnancy and birth as well as after birth. This information will help the audiologist to determine if there are any risk factors that would indicate that the baby or child is at an increased risk for a progressive or late-onset hearing loss.
A physical examination is done to evaluate the outer ear, ear canal and eardrum.
Tympanometry is done to evaluate the condition of the middle ear system, the mobility of the eardrum and the conduction of sound by the middle ear bones.
Oto-acoustic emissions (OAEs)
The cochlea has outer and inner hair cells. A cochlea that is functioning normally not only receives sound, its outer hair cells also produces low-intensity, measurable sounds called OAEs. The OAE measurement is an objective measurement to determine the integrity and functioning of the outer hair cells.
As a child matures and is able to provide consistent hearing results behaviourally, hearing information can be plotted for each ear specifically. During audiometric testing, the audiologist find the softest level (threshold) at which a child can detect sound at different frequencies (pitches). From this information, a graph of the child’s hearing/hearing loss, called an audiogram, is created.
In infants, visual reinforcement audiometry (VRA) is recommended. After about 2 years of age, a toddler can be trained for conditioned play audiometry.
In the case where an infant/child has a one or more risk factor for hearing loss or has not passed one or more of the above mentioned measurements and/or there is a concern of hearing loss, the following advanced tests will be recommended and performed:
Auditory Brainstem Response (ABR)
ABR testing is an electrophysiological measurement that allows the audiologist to obtain information about the condition of the inner ear and/or auditory nerve. It is a critical procedure as it is an accurate and reliable predictor of hearing loss in infants who are too young to respond to behavioural testing.
Auditory Steady State Response (ASSR)
ASSR testing is another electrophysiological measurement of a baby’s hearing. The ASSR may provide more frequency specific threshold information for infants/children who have severe to profound hearing loss. (Reference: www.infanthearing.org)