The Audiologists at Cairns Audiology Group are experienced in the assessment of Auditory Processing problems in both children at or above 7 years of age and adults using the latest evidence based protocols and testing methods.
Auditory Brainstem Response (ABR) Assessment:
ABR is a non-invasive way for the Audiologist to assess the function of the auditory nerve in neonates and infants under 6 months of age and those with developmental delays who cannot perform behavioural assessments. ABR is usually requested by a Specialist such as a Paediatrician or via the Neonatal Hearing Screening Program.
ABR is performed by placing 3 special stickers called electrodes onto the infant’s head (one on the high forehead and one behind each ear). The electrodes will detect specific neurological markers which indicate the hearing nerve’s response to specific sound stimulus, which is delivered to the ears via headphones. The loudness of the stimulus is gradually decreased until a response is no longer detected from the auditory nerve. The softest level at which these neurological markers is present corresponds to the child’s hearing threshold for that specific sound stimulus. This assessment allows the audiologist to accurately predict the infants hearing thresholds across a range of pitches or frequencies without a behavioral response required from the infant themselves.
What can you do to improve the ABR response?
The ABR is best conducted when your child is asleep or in a relaxed quiet state as movement and noise can interfere with the results. In order to ensure the best possible results can be obtained for your child;
- Keep your infant awake before the hearing test so that they will sleep soundly during the evaluation.
- Try to arrive 10 minutes before your scheduled appointment time and feed your infant just prior to the testing to ensure a relaxed, comfortable, and sleepy baby. If your child is bottle fed, bring additional formula in case feeding is required during the assessment.
- Bring a blanket or stuffed toy that your infant is familiar with to make them more comfortable during the evaluation.
- Allow for a 2 hour block of time in your schedule for the audiologist to test the infant. (Sometimes more time is needed for the evaluation if the infant does not want to quiet down and sleep right away.)
Sometimes additional appointments are required if your child does not settle well.
Visual Reinforcement Audiometry (VRA):
As your child gets older (around 9 months of age) and gains control of their behavioural reflexes, more specific threshold assessment can be performed using Visual Reinforcement Audiometry (VRA).
During VRA your child will sit on your lap or at a small children’s table between 2 calibrated speakers or with earphones in. A sound of specific frequency is presented and the audiologist will watch your child for a response such as an eye-shift, startle reflex or head turn. If a reliable response is detected your child will be rewarded with activation of a cartoon on a screen mounted near the speaker. Your child’s attention is then distracted back to the midline so the process can be repeated with sounds of varying frequency and loudness until reliable thresholds are detected across the speech range.
If the VRA test is performed through the speaker it is known as a “free-field or sound-field assessment” and does not give ear specific information as the better ear will always respond, therefore sound-field assessment cannot rule out a unilateral hearing loss. However, if your child will tolerate earphones, each ear can be assessed separately.
At approximately 3.5 years of age, a toddler can be trained or conditioned to engage in play audiometry. During this assessment your child will be shown how to perform a repetitive play task, such as placing a marble into a box, each time they hear a sound. This assessment is usually performed under headphones and can give individual or ear specific hearing threshold information.
Tympanometry is an objective test of middle ear function which can assess the health of the tympanic membrane (ear drum), eustachian tube and middle ear space.
During this assessment the audiologist will place a probe int your child’s ear which will introduce a gentle varying pressure into the ear canal and measure the compliance or movement of the middle ear system in response.
Tympanometry takes just a few seconds to perform and the result can indicate to the audiologist if there is fluid or effusion in the middle ear pace (glue ear), a perforation of the tympanic membrane or the presence of other middle ear conditions.
Speech audiometry involves the measurement of a child’s ability to hear and understand speech stimulus which is presented via headphones or in the free field via speakers. This assessment provides not only a way to confirm the hearing thresholds obtained during behavioural assessment but also gives a prediction of the child’s ability to discriminate normal conversational speech.
If your child is too young to perform conventional speech audiometry assessment, an alternate form of assessment known as the Pediatric Speech Intelligibility Test (PSIU) can be attempted down to approximately 3 years of age. This test involves the child selecting a standardized picture from a set of 4 which corresponds to the speech stimuli they are presented with.
Otoscoustic Emmissions (OAEs):
Otoacoustic Emissions (OAEs) are sounds which are generated by the movement of the outer hair cells of the inner ear (or cochlea) in response to an auditory stimulus which is delivered to the child’s ear via a probe in the ear canal. The strength of the Otoacoustic Emission can help the audiologist to determine the origin of a hearing loss detected on ABR or during behavioural audiological assessments.
More information on Auditory Processing Disorders and their management