An Underwater Stethoscope Based on a Directional Hydrophone, For Use in Dolphin Rehabilitation and Diagnosis
Abstract
Based upon the experience of the Texas Marine Mammal Stranding Network, stranded dolphins that enter into rehabilitation often experience elevated levels of stress. A foreign environment, interactions with humans during procedures and other necessary aspects of animal care, contribute to this stress.
During rehabilitation, stress levels are typically measured by obtaining respiration and heart rates manually. However, a hydrophone with a custom made suction cup can be used as a tool to listen to sounds arising within the heart, lungs and abdomen while in an aquatic environment. Therefore, this underwater stethoscope is beneficial not only in monitoring stress levels, but also in diagnosing conditions such as pneumonia and intestinal obstruction. The hydrophone can be used for this due to the fact that conditions such as these all cause changes in quality or pattern of sound.
Cetacean Research Technology manufactures the hydrophone, model C54XR, used for this research. Cetacean Research Technology also created a silicon suction cup attachment for the hydrophone. The device used to record hydrophone readings is a Sony TCM-200DV handheld digital tape recorder with KOSS UR40 earphones.
Preliminary studies performed with the use of this directional hydrophone, support the accuracy and clarity of its recordings. This specialized hydrophone is beneficial in a rehabilitation setting by allowing vital signs to be monitored without the added stress that can be caused by removing a dolphin from the water. By eliminating this factor, it is anticipated that a more accurate baseline will be obtained. Current studies using the directional hydrophone will enable the collection and interpretation of recordings from a larger number of dolphins. With the use of this data, normal sounds will be established and abnormalities can be distinguished. Through further studies, values obtained from dolphins in rehabilitation can be compared with those in the care of man to determine the difference in stress levels during animal care procedures.