Effects of long-term WR on ABR (auditory brainstem response) hearing thresholds. a–f, ABR hearing thresholds from the 3-month-old NWR, 24-month-old NWR, and 24-month-old WR groups were measured at 4 (a), 8 (b), 16 (c), 32 (d), 48 (e), and 64 (f) kHz (n = 5–10). Data are shown as means ± SEM. *p < 0.05 versus 3-month-old NWR group. #p < 0.05 versus 24-month-old NWR group. g, ABR hearing thresholds at all frequencies from the 3-month-old NWR, 24-month-old NWR, and 24-month-old WR groups.