Fig. 2. Auditory brainstem response (ABR) waveforms (dark traces) and oscillograms of each sound stimulus (light traces) of the different species investigated at 20 dB above mean hearing threshold of each particular species within (A) siluriforms, (B) cypriniforms and (C) perciforms. All stimuli were recorded under water with the hydrophone 2 cm away from the animals. The amplitudes of the sound waveforms were adjusted to fit to the proportions of the ABR waveforms.