Fig. 3.

Amplitude of the P1 waveform following tone pip attenuation in noise exposed rats. The mean amplitude of P1 in response to (A) 12 kHz, (B) 16 kHz, (C) 24 kHz and (D) 30 kHz tone pips for each set of ABR measurements and fitted with lines of best fit. For each frequency tested, the amplitude of P1 decreases as the tone pips are attenuated. There was no significant difference between the P1 amplitudes from the ABR measurements at any stimulus intensity in response to the 12 kHz and 16 kHz tone pips. However, significant decreases in P1 amplitude in comparison to the 1st ABR were observed during the second and final ABR experiments in response to the 24 kHz and 30 kHz tone pips (p < 0.05). The fitted lines show no change in the gradient of the curve following noise exposure.