Paediatric Audiology RHS 472 VRA

VRA (Visual Reinforcement Audiometry) Overview

• Target age: 6-36 months.
• Uses illuminated and animated toys as reinforcers.

Reinforcer Setup

• Reinforcers should be stored in a moveable cabinet with a smoked Perspex screen, preventing visibility until illuminated.
• A switch in the observation room controls toy animation and brightness.
• At least two toys should be independently controllable on each testing side to vary rewards.

Loudspeaker Positioning

• Loudspeakers positioned at a 90° angle from the child, 1 meter away, to ensure efficient sound delivery.
• Positioning at ear level enables better conditioning and accurate Minimum Response Level (MRL) establishment.

Reinforcer Positioning

• Reinforcers should ideally be at 90° azimuth for clearer head-turn elicitation.
• Placed 1-2 meters away and at the child’s head level, allowing for immediate association with sound stimuli.
• Proximity between loudspeaker and reinforcers enhances conditioning, but should not interfere with soundfield calibration.

Child and Tester Positioning

• Infants (5-12 months) seated on a parent’s knee or a secure high chair; older children on a low chair.
• The child must be positioned at a predetermined calibration point with an engaging activity table in front.
• Tester 2 sits opposite the child with suitable toys within reach for engagement.

Tester Positioning and Communication

• Tester 1 needs a clear view of both the child and Tester 2’s actions.
• Audiometer and reinforcer control box should be easily accessible for Tester 1.
• Effective two-way communication between testers is critical; use of discreet communication systems recommended.

Hearing Protection

• Hearing protection (muffs/plugs) shall be available for parents, observers, and testers.
• Essential for those suspecting severe or profound hearing loss to ensure safety during sound field stimuli.

Stimuli Types

• Varied stimuli should be used to maintain the child's interest, including warble tones and narrow band noise (NBN).

Stimulus Delivery Methods

• Supra-aural earphones can collapse the ear canal and are cumbersome, while insert earphones provide better direct sound delivery.
• Insert earphones reduce transcranial transmission of sound but are unsuitable for infected or obstructed ears.

Subject Preparation Procedures

• Parents and child sit in the testing room; history taking helps the child settle.
• Assess child’s alertness; adapt testing timing based on restlessness.
• Check developmental and visual status; ensure proper head control to respond.

Conditioning and Test Procedure

• Stage 1 (Conditioning): Noise + visual reinforcement prompts head turn (classical conditioning).
• Stage 2 (Testing): Noise prompts head turn or no reinforcement if the head doesn’t turn (operant conditioning).
• Conditioning trials may be needed for consistent head turns; begin with a 2-kHz stimulus at 60-70 dB HL.

Measurement of Minimum Response Levels

• Suitable table-top activities maintain the child’s forward position and alertness.
• Avoid cues linked to stimulus presentation to prevent false responses.