Audiologic assessment in infants

The purpose of this review is to provide the reader with current information regarding the standards for audiologic assessment of infants and very young children. The nature of the appropriate test battery and the need for adjusting test procedures to meet the specific needs of infants and toddlers are emphasized. The basic measures in the audiologic test battery include frequency-specific threshold tests by air and bone conduction, predicted by electrophysiologic measures when necessary; immittance measures including tympanometry and acoustic reflex using a high-frequency probe tone for infants under 4 months of age; and otoacoustic emissions. The ABR can be used with frequency-specific stimuli to predict the audiogram in newborns with a great deal of accuracy. Newer techniques, such as Auditory Steady State Response, are promising but need further study before they can be used reliably to predict hearing levels in infants. Finally, infants with hearing loss can be fit with amplification using prescriptive formulae, such as the Desired Sensation Level, which give appropriate hearing aid characteristics for infants based on their hearing thresholds. These fittings must be verified using objective electro-acoustic measures tailored to infants. Infants failing newborn hearing screenings can be evaluated by audiologists to predict all necessary audiologic data and those found to have hearing loss can be fitted with appropriate amplification in the newborn period. Procedures must be carefully tailored to this age group.