Brain stem (ABR) and middle latency (MLR) auditory evoked responses in infants.

We examined ABRs and MLRs for click and/or 500-Hz tone pip stimuli in infants (36-44 weeks conceptional age) admitted to the NICU and measured the threshold and detectability of those responses. We took the threshold indicators of those responses as Jewett V for ABR measurement and wave PO Nal Na2 for MLR measurement. Thresholds of MLRs for click stimuli were almost equal to those of ABRs for click stimuli. On the other hand, thresholds of MLRs for 500-Hz tone pip stimuli were slightly worse than ABRs for click stimuli, the average differences being less than 10 dB. Wave Po Nal Na2 are the best threshold indicators of MLRs in infants, but the diagnostic significance of wave Pa was questionable in our measurements.