FIG. 8.

DPOAE level shifts (LS) as a function of f2 frequency measured following noise exposure at 8 h (A), 24 h (B), 7 days (C), and 21 days (D). Compared with noise-exposed controls, animals treated with NAC/HPN-07 showed a clear reduction (or a tendency for reduction) in LS over the entire frequency range for points beginning at 24 h post-exposure and continuing through the 21-day terminal time point. A significant effect was present at 7 days for 3–6 kHz and 21 days for 6–8 kHz. Data were plotted as mean ± SEM. n represents the number of ears. Data was analyzed using a two-way ANOVA with the Bonferroni test, *p < 0.05, **p < 0.01, ***p < 0.001.