Performing aided testing via Visual Reinforcement Audiometry

In adults and older children, traditional speech testing is used as a method of establishing whether the patient's hearing device(s) are working as desired. In much younger children, this isn't yet possible due to attention and their still developing speech and language skills. This video will explore how behavioral testing such as Visual Reinforcement Audiometry can be used with hearing aids in situ to assess a patient's aided benefit in this young age group.

You can read the full transcript below.

What is visual reinforcement audiometry?

VRA – or visual reinforcement audiometry – is a behavioral method of performing a hearing test. It can be used to test patients from around seven months to about two and a half years of age. Sufficient neck and trunk control is required for the patient to sit upright and turn their head to the stimulus and reward.

How to perform VRA

VRA is performed by conditioning the child to perform a head turn in response to the stimulus delivered. This response is then rewarded and reinforced by presenting a visual reinforcer, such as displaying an animated toy or an image or video on a screen.

VRA can be performed via sound field, headphones, insert earphones and bone conduction. It can also be performed via sound field with the child's aids in situ.

Here, we can see an 11-month-old patient performing VRA unaided via the bone conductor with toy reinforcers to her right side which light up and animate when she delivers a positive head turn in response to the stimulus.

What is the goal of aided VRA?

When performing aided VRA, the goal is to assess how well the patient can hear via their hearing instrument. This can help provide confirmation that the patient's hearing instrument is working as desired.

This can be reassuring to the parents and also provide encouragement to continue persisting with hearing instrument usage, which is not always well tolerated in this age group, regardless of benefit.

Assessing the patient via aided testing can also assist in determining if and what changes might be required to their amplification settings if the results are not as anticipated or hoped for.

Aided testing can also provide support in deciding whether to change the power of an instrument, use an alternative device, or make use of assistive listening devices for additional support.

Aided VRA stimuli

Aided VRA can be performed using a range of stimuli including warble tones or narrowband noise. However, the main clinical question relates to whether the patient can hear speech sounds.

Utilizing speech-like stimuli for aided VRA testing allows us to establish whether the patient has sufficient and appropriate amplification to allow for speech to be detected, in order to support the child's speech and language development.

Examples of such stimuli include the LING-6 sounds, which are six different phonemes covering the full speech spectrum.

/oo/ and /mm/ in the low frequencies, /ee/ and /ah/ in the mid frequencies, and /sh/ and /ss/ covering the high-frequency region.

Alternatively, the ManU-IRU stimuli, which were developed for aided cortical testing, have also been validated for aided VRA testing by both the original authors [1] and the Ladies in the Van study [2].

Aided VRA test technique

When performing aided VRA, it is important to condition the child in the same way as you would for standard unaided testing, using an easily supra-threshold level.

Once successfully conditioned, a bracketing technique should be used to test down to lower levels. Given the limited attention span of the age group suited to VRA, larger step sizes are recommended than are used for pure tone audiometry, typically reducing the intensity level in 20 dB steps and ascending by 10 dB steps.

The aim of testing is to establish the minimum response level at which the patient responds to the stimulus presented. To ensure reliability of the results, the final level should be determined based on greater than 50% positive head turns. In other words, to at least 2 out of 3 stimulus presentations at the level in question.

Aided VRA interpretation

As VRA requires a head turn, the reinforcer toy or screen should be located at a 90-degree angle to the patient in order to elicit a significant and clearly identifiable head turn.

Typically the free-field speaker used for presenting the stimulus is also located to the side in order to support the conditioning of this head turn. However it is important to recognize that even though the response, reinforcer and speaker may be to one side or the other, this does not mean the responses relate to the side tested.

Any free-field testing, whether aided or unaided, cannot be interpreted as ear-specific, as either or both ears or hearing aids when fitted could be detecting the stimuli presented and generating the head-turn response.

Aided VRA testing is an example of binaural testing, and any results obtained must be interpreted as such.

If the patient is aided monaurally, then interpretation must be taken with care to account for the state of the other ear.

If the hearing in the other ear is normal, or considerably better than the aided ear, responses to free-field testing may be generated primarily by this ear rather than the aided side.

If the unaided ear has a greater loss than in the aided ear, then responses may be attributable to the aided side.

And there may be cases where this is not clear.

It is possible to use ear plugs and ear defenders to try to isolate one ear from the other.

However, it is important to remember that the purpose of performing aided testing is to establish whether the patient is deriving benefit from the hearing aid or aids as they would be used in the real world.

If a patient is aided monaurally and has good hearing in their unaided ear, then our primary focus should be establishing how well they can access speech sounds using both the aided ear and the unaided ear as a pair together.

Where does aided testing fit into the fitting pathway?

Aided testing forms a vital part of the patient fitting pathway. With newborn hearing screening programs facilitating infants being diagnosed younger than ever, hearing aids are likewise being offered and fitted at very young ages.

VRA becomes possible at around seven months of age and can be used not only to reassess the patient's hearing levels using traditional stimuli, but also allows for aided testing to be performed to validate how successful the hearing aid fitting has been.

The results of aided testing help to guide whether adjustments and changes to the hearing aid settings are required in order to ensure the best outcomes for these young patients who are not yet able to self-report or perform more advanced speech testing.

Related courses

• Advances in Pediatric Hearing Assessment
• Validation in Pediatric Hearing Aids

References

[1] Stone, M. A., Visram, A., Harte, J. M., & Munro, K. J. (2019). A Set of Time-and-Frequency-Localized Short-Duration Speech-Like Stimuli for Assessing Hearing-Aid Performance via Cortical Auditory-Evoked Potentials. Trends in hearing, 23, 2331216519885568.

[2] Visram, A. S., Stone, M. A., Purdy, S. C., Bell, S. L., Brooks, J., Bruce, I. A., Chesnaye, M. A., Dillon, H., Harte, J. M., Hudson, C. L., Laugesen, S., Morgan, R. E., O'Driscoll, M., Roberts, S. A., Roughley, A. J., Simpson, D., & Munro, K. J. (2023). Aided Cortical Auditory Evoked Potentials in Infants With Frequency-Specific Synthetic Speech Stimuli: Sensitivity, Repeatability, and Feasibility. Ear and hearing, 44(5), 1157–1172.