Comparisons of Auditory Steady State and Auditory Brainstem Response Thresholds in Infants with Normal Hearing and Conductive Hearing Loss

This study investigates how well the air- and bone-conduction auditory steady-state response detects mild conductive hearing loss compared to the auditory brainstem response in young infants. Air-bone gap sizes are compared between infants with normal hearing and conductive loss using a two-group cross-sectional design. Twenty-three (500 Hz) and 22 (2000 Hz) infants (0-6 months of age) with normal hearing and 15 (500 Hz) infants with conductive loss were recruited from newborn hearing screening. Thresholds were obtained to frequency-specific air- and bone-conducted stimuli. There were no instances of conductive loss at 2000 Hz. 500 Hz mean thresholds and air-bone gap sizes were compared. Sensitivity and specificity for identifying conductive loss were measured. Overall, mean bone-conduction thresholds were similar between groups, and mean 500-Hz air conduction thresholds were higher with larger air-bone gap size for infants with conductive loss. Sensitivity and specificity for identifying conductive loss was highest for air-conduction auditory brainstem response threshold measurement compared to screening and auditory steady-state response threshold measurements. Compared to the auditory brainstem response, the variability of auditory steady-state response thresholds and air-bone gap size was too great to reliably separate normal hearing from mild conductive loss. More research is needed using infants with varying degrees of hearing loss at multiple frequencies to fully assess the appropriateness of the auditory steady-state response as a clinical diagnostic tool for an infant population.