Maximum length sequence auditory evoked brainstem responses in human newborns and adults.

Overview

Experiment 1 investigated developmental differences at high stimulus rates by using maximum length sequences (MLSs) and cross-correlation techniques to recover auditory evoked brainstem responses (ABRs). Reliable MLS ABRs were recorded in all of the newborns tested at the highest rate presented (minimum interpulse interval = 1.1 msec). Interpreting developmental rate effects from latency and amplitude shifts is problematic. Identification of higher order kernals offers new information concerning developmental rate effects. Kernel slices were measured at lower rates in more adults than newborns, suggesting that the newborn auditory system is less sensitive to temporal nonlinearities than the mature auditory system. This runs counter to developmental rate studies using conventional stimuli. Experiment 2 investigated developmental differences at high rates due to varying stimulus intensities. MLS wave V intensity functions were less steep than conventional wave V intensity functions. MLS thresholds were also higher than conventional thresholds (primarily due to the newborn data). Without equating for signal-to-noise ratio, it is difficult to make unambiguous conclusions concerning the observed developmental differences.