During the first 7 months of life, C57BL/6 mice demonstrate progressive sensorineural hearing loss for high frequencies (>12 kHz), with little loss of sensitivity for lower frequencies. Auditory brainstem responses (ABRs) were obtained from C57 mice of both sexes aged 1 to 7 months. Stimuli (1 ms duration, 0.1 ms rise‐fall, 10/s rate) of two types were used: For “low‐pass” (LP), stimuli frequencies above 12 kHz were filtered from white noise; for “high‐pass” (HP) stimuli frequencies below 12 kHz were filtered. A wound clip over the vertex served as the active electrode and a bite bar was the reference. Thresholds of ABR wave I progressively increased by about 20 dB (re:20 μPa) by 7 months for the HP stimulus but increased by only 5 dB for the LP stimulus. Ratios of amplitudes of later ABR waves to early waves increased with age for high intensity stimuli. Amplitude‐intensity function slopes of waves IV and V (but not I‐III) increased with age. Both effects were more pronounced for HP stimuli. Sex differences were not observed in any of these findings. In summary, early and late ABR waves of hearing‐impaired C57 mice change in different ways with age, and the changes depend on the frequency spectrum of the stimulus. [Supported by a Research Career Development Award and a grant from NIH.]