A simple small‐scale model of a generalized harbor entrance with rectangular resonators was set up. Using simple electronic equipment and sound waves of the order of 1000 cycles, the geometry for resonance was determined. The results are compared with those obtained from a hydraulic model, using gravity waves of similar wavelength. It was found that the results were not influenced by imperfect boundaries or reasonable changes in frequency. It is concluded that the results are sufficiently accurate to warrant further development of the method as an aid for harbor design, particularly in view of the simplicity and size of the equipment.