Acoustics of a standing wave tank for studying the hearing capacity of fish.

In a standing wave tank responses of fish to sound stimuli used to investigate the hearing capacity of fish may perhaps be affected by unintended stimulation of the lateral line. Uniform oscillatory water flow patterns do not stimulate the lateral line. Departures from uniformity were derived from measurements to acoustic pressure and particle velocity at 5-cm spacings around the center in our standing wave tank containing six transducers suspended along three axes that are perpendicular to one another. These measurements are compared with the results of a model in which negligible influence of the tank wall and an incompressible water column in the tank are assumed. Deviations of computed values from measured values of sound pressure and the principal velocity components are less than 5 dB. The model underestimates velocity components perpendicular to the principal component. However, the model does appear a reliable aid for estimating the spatial function of sound pressure and velocity from the values of p and v measured at the tank center. Upper limits for the relative velocities between the fish body and the water can only approach threshold values for the lateral line stimulation under worst conditions (i.e., a velocity node at the tank center) in this setup.