TEHDI- Assumptions Underlying Audiologic Evaluations of Newborns and Infants
Before defining our protocol for infants with hearing loss, the participants agreed to some underlying assumptions. Once that agreement was unanimously reached, the process of defining audiologic evaluation protocol was simplified. The following are our underlying assumptions:
- Hearing aid fittings and habilitation, including referral to the local Early Childhood Intervention (ECI) program, will be initiated as soon as the hearing loss has been identified. Unless medically contraindicated, there is no defensible rationale for delaying hearing aid fitting.
- The auditory brainstem response (ABR) provides valuable and reliable estimates of hearing sensitivity in very young children.
- ABR thresholds provide sufficient data for establishing hearing aid fitting targets in infants. HOWEVER, click-evoked ABR thresholds alone are inadequate for hearing aid fitting, because they assess mid frequency sensitivity only, and provide no information regarding configuration of the loss.
- For ABR to be useful in this role, frequency specific measures must be included.
- Bone conducted click ABR measures are essential for defining the type of hearing loss in infants. It is possible to hand-hold the bone vibrator against an infant's head, to avoid the problems encountered with the traditional metal headband.
- As a cross-check measure for the ABR, Otoacoustic emissions (OAEs) should be evaluated prior to fitting hearing aids on infants. Hearing aids should not be fitted on those who demonstrate normal OAEs.
- Audiologic and habilitative protocols appropriate for well-babies will differ from those appropriate for high-risk babies.
- Diagnostic audiometry in infants is an ongoing process. Behavioral testing should be attempted as soon as possible, to supplement ectrophysiologic data. Ear-specific information may be obtained as early as 6 months of age using VRA/COR procedures.