Performing good quality visual reinforcement audiometry (VRA) can be a complex task and it is important to be aware of possible pitfalls and sources of error. The British Society of Audiology's recommended procedure has highlighted the most common of these pitfalls and in this video, we'll take a look at how we can address some of these. Find the full transcript below.
The first pitfall listed in the BSA recommended procedure is inadequate test setup and communication between testers. To address this, I would urge you to review the video on VRA preparation and to assess your VRA testing room and environment with a critical eye to see if any improvements can be made.
One of the best investments you can make is providing a two-way communication system for your testers. It's also worth discussing the roles of the testers as a clinical team to ensure everybody knows and is aware of their responsibilities and all team members feel confident fulfilling their roles.
It can be easy to inadvertently attempt to condition to sub-threshold stimuli if the child's hearing levels are unknown. Selecting an appropriate conditioning level can be guided by the case history and any other test results including previous hearing levels if available.
If conditioning is not working, trying vibrotactile stimulation can help to establish whether the patient can be conditioned to this type of task using a non-auditory stimulus. This can indicate that they possibly couldn't hear the auditory stimulus, or they are simply not ready for this type of task.
Using insert earphones or headphones offers the option of going louder than is safe in the sound field. But caution should be used to avoid presenting at uncomfortably loud levels.
Always make sure you confirm that conditioning has been achieved by checking for those two independent head‑turn responses before progressing with testing.
Accepting a movement other than a clear head turn or accepting a checking response is one of the most problematic errors made in VRA testing. It is important to focus on that clearly defined head‑turn response and for the testers to be confident in what that head‑turn response looks like for an individual child. Being able to differentiate between that and a checking response, which is often much faster and briefer, is crucial.
Using ‘no‑sound’ trials throughout testing can help to identify checking responses.
Reading the child and the testing scenario allows for the optimum timing of stimulus presentation.
It is also important to avoid introducing tester response bias. If the tester believes or wishes that the child's hearing is normal, then this can lead to a lack of objective interpretation. We should never assume normal hearing or be trying to prove normal hearing. Our role is to assess and record results whatever they may be.
The second tester must be aware of how they play and interact with the child. Phasing their attention to a slow or a complete stop at the same time as the stimulus presentation occurs risks cueing the child and recording a false positive response.
Maintaining appropriate engagement throughout testing is essential.
The second tester must ignore the stimulus presentation and keep up their play. The head‑turn response of an engaged child is a reliable response.
Cues can also be provided by the parents. So they should be instructed appropriately and both testers should remain alert to any potential cues.
It is understandable to want to obtain as many results as possible in a given session. However, testing one or two frequencies reliably is worth much more than rushing through four or more frequencies with questionable reliability. It is always worth investing time in correct, effective conditioning at the start of the session rather than hurrying down to quieter levels.
VRA does require patience and if stimuli are presented rhythmically, then the child's responses can also become rhythmic. Varying stimulus presentation timing and using a healthy number of ‘no‑sound’ trials will add to the reliability of the test.
Once again, we should never assume normal hearing or be hoping to record normal hearing.
VRA is a complex test to perform well, and it is vital that both testers are aware of potential pitfalls and how to avoid these. Clinician experience is valuable, and care should be taken to support inexperienced staff to develop their VRA skills.
‘No‑sound’ trials are one of the best tools to help improve the reliability of the test and certainty of the results. Once again, it is so important not to assume or hope for normal hearing results.