Figure 3. Noise-induced permanent threshold shift.
DPOAEs recorded in three animals before and 1 day, 7days and 28 days after noise exposure indicate a shift in the permanent hearing threshold. The distortion product amplitudes at f2 frequency 8 kHz and 16 kHz showed a mild recovery 7 days after noise exposure and a moderate recovery after 28 days. Nevertheless, the amplitude was 10 to 20 dB lower than the pre exposure levels. The results are expressed as mean ± standard error, n = 3.
