Behavioral auditory assessment of young infants: methodological limitations or natural lack of auditory responsiveness?

The determination of auditory thresholds by means of behavioral techniques in young infants can be difficult. This could be the result of limitations in methodology, a lack of observable auditory responsiveness, or both. In the current study, 2- and 4-month old infants were tested under enhanced conditions for obtaining behavioral responses (i.e., salient auditory stimuli, reduced visual distractions, reinforced correct responses). A two-interval, forced-choice task with four intensity levels was used. Although a behavioral threshold was obtained for the 4-month-olds, threshold determination for the 2-month-olds remained elusive. In light of the current findings and previous studies of visual acuity of infants, these results suggest a lack of behavioral responsiveness to auditory stimuli for the younger infants rather than methodological limitations. With infants in the 2-month-old age range, clinical audiologists should expect few behavioral responses to auditory stimuli at intensity levels below those that elicit startle responses.