Fig. 2.

Waveform of a hammer strike and induced swimbladder displacement and sound for a male 432 g toadfish. Note that after the first hit H1, the hammer administered a second much weaker strike H2. Displacement occurred over two cycles: an initial compression of the swimbladder (negative or N1 wave) followed by an expansion (positive or P1 wave) and a greatly attenuated second cycle exhibiting rapid damping. The sound waveform also exhibited two cycles (N1 and P1 followed by N2 and P2). Cursors mark the beginning, peak and end of the hammer strike. Note that the first cycle of the sound waveform is largely complete by the peak of the hit, which occurs at P1 of displacement, and that sound is complete before the second hit. The space after the beginning vertical line on the displacement waveform indicates a 1.5 ms delay in the movement of the bladder at the measurement site.