Auditory brainstem responses. A, ABR thresholds for click and 12 kHz tone burst stimuli are shifted to a comparable degree in Bsngt and BsnΔEx4/5 animals compared with their respective littermates, the latter displaying strain-dependent differences. B, Grand averages of ABR waves in response to 100 dB (mutants) or 80 dB (WT) click stimuli from Bsngt (red, n = 7) and BsnΔEx4/5 (purple, n = 6) mutants and WTgt (black, n = 9) and WTΔEx4/5 (gray, n = 6) controls, illustrating a pronounced reduction in amplitudes and minimal delay of all ABR peaks. ABR waveforms in BsnΔEx4/5 heterozygous animals were equivalent to WTΔEx4/5 (data not shown).