Once a child is over six months of age, they will likely move on from ABR test to a more response based behavioural test: a Visual Reinforcement Audiometry (VRA). But what is a VRA test and what do its results mean for your child?
VRA testing usually takes place from six months up to around three years of age when conditioned play audiometry (CPA) will be introduced. Tones of differing frequency (pitch) and intensity (volume) are played and a puppet illuminated when the child responds to the sound as a reward. Positive responses are plotted on an audiogram, showing frequency against volume so the audiologist and parents can see exactly what frequencies and intensities hearing loss is occurring at. This graph also helps to establish whether the child’s hearing loss falls into the category of mild, moderate, severe or profound If earphones or bone conduction pads are used, each ear can be assessed individually. However, if a child is not cooperative with earphones and sound field speakers are used, only overall hearing ability can be properly assessed.
To start the process, in a quiet room, the child will sit on the parent’s lap, or alone if they are slightly older. Ear phones will be inserted into the child’s ears (though sound field speakers can be used if your little one finds earphones too distressing). There will be two audiologists present to carry out the test. One tester will sit in front of the child with toys to engage the child’s view and attention, while another tester will sit further in front with a view of the child’s face so observe responses to sound. Alongside the child (at approximately 90 degrees) on each side, there will be a dark, smoke screen cabinet and a speaker. Using pure tone audiometry, sounds will be played into the ears individually from each speaker, and when the child hears the sound, they will theoretically turn towards it and be rewarded for their response by a moving, illuminated puppet that appears in the corresponding cabinet: hence the term ‘visual reinforcement’.
At the beginning of the test, the sounds will be played at an easily audible level and the tester will alert the child to the puppets, conditioning them to the process, before the volume is decreased as the test progresses, to adequately test hearing thresholds. The tones will be played at random intervals to avoid the child anticipating the sound, compromising the integrity of the results. Often following on from weak responses on the test, bone conduction pads may be attached to the head just behind the ears to rule out conductive hearing loss.
Diagnosing and accurately measuring hearing loss in a toddler can be a challenge. If your child is having this test at six months, it’s likely they may have already failed the OAE or ABR testing. Interestingly, in comparison, the results on a VRA are considered to be more accurate but less reliable than on an ABR. This is because responses are dependent on behaviour and it can even be possible to ‘fluke’ a pass on a VRA; something that is highly unlikely on an ABR test. However, with a cooperative, focused toddler, the results of a VRA should be accurate enough to confidently use to configure hearing aid or cochlear implant settings, even for a mild to moderate hearing loss.