Responses of the swimbladder of the carp to sound stimulation

The oscillations of the swimbladder anterior chamber of the carp ( Cyprinus carpio) following stimulation with tones of 300–1500 Hz were studied by the method of holographic interferometry. The oscillation amplitude appeared to be maximal at frequencies close to the resonance frequency of an air bladder of equivalent volume as well as at frequencies corresponding approximately to the second and third harmonics of the resonance frequency. A change in the frequency of the sound signal or in the instantaneous pressure amplitude could result in spatial displacement of the oscillation centers on the swimbladder wall. The interference picture which resulted from recording the swimbladder oscillations over the tested frequency range was not observed on the holograms recorded within 20–24 h after the fish had been killed.