Noise-induced DPOAE input/output functions at f2 frequencies of 6, 8.6, 13.2, 16, 24 and 30 kHz; L1 intensity shown on abscissa. Pre-exposure DPOAE I/O functions shown as 95% confidence interval around the mean (blue shaded area). Mean DPOAE I/O functions obtained during (A) 45, 53 and 60 dB SPL noise exposures and (B) 68, 76, 84 and 92 dB SPL noise exposures. DPOAE input/output functions that were significantly different from pre-exposure input/output function indicated by p value in the legend of each panel (see Table 1 for details).