SUMMARY

The original subject of this research was to determine if any rocking motion was present in an otolith when subjected to a plane acoustic wave. Since measuring the motion of an actual otolith proved to be beyond the limits of resources, a hemisphere suspended in water was ultimately used instead. The hemisphere was chosen because it was the easiest shape to measure accurately, and had the asymmetry necessary to be a good substitute for an otolith. Measurements were taken along the hemisphere from top to bottom to determine if any rocking actually occurred, and the vertical motion was also measured. The displacement of the hemisphere at each point was determined by using an ultrasonic transducer and other sensors. The results from this experiment showed a small amount of rocking, but far less than predicted. The vertical motion was around ten times greater in magnitude than the rocking motion at the edges, so the rocking did not greatly affect the overall motion of the hemisphere. Additional follow-up experiments were then conducted to determine if any experimental artifacts contributed to the overall result. Additional testing was then done on a series of semicircular cylinders to determine if their motion matched theoretical predictions. In this case, rocking was also present and was found to be on the order of the motion of the hemispheres. This motion was found to be smaller than published theoretical results. These results can ultimately be used to predict and understand the motion of more complex geometries, like otoliths. While a rocking motion was present in all cases, it would most likely be too small to be used in sound directionalization in fish.