An electrically conducting fluid in a magnetic field generates forces as a result of the application of an electric current in the fluid, and a wave motion in the fluid generates an electromotive force. This effect has been applied to an underwater acoustic transducer: liquid state electromagnetic transducer. For the two acoustic ports and the electrical port, three‐port equations have been presented whose coefficients are functions of such physical parameters as the duct size, fluid conductance, wave speed in the duct, and magnetic flux density. In this research, to examine the analytical model, salt water was used in a square duct of anodized aluminum, which has a pair of facing copper electrodes on the inside walls of the duct. A magnetic field was applied externally by an electromagnet. A series of measurements to evaluate every coefficient of the three‐port equations was performed. Good experimental support for the model was obtained.