Development of Improved Noise Transducer for Animal Noise Monitor

Studies of aircraft noise effects on wildlife have been hampered by an inability to measure animal noise exposure in the wild. USAF supported development of a retrievable, portable Animal Noise Monitor (ANM) in 1989 and an enhanced second generation version during 1994-1995. The weakest component of the current design is the electret microphone. The proposed object of this research is to investigate use of a thin film transducer mounted inside the ANM case. The thin film is a passive element that does snot consume electric power and eliminates many environmental constraints of microphones. Preliminary experiments testing film performance bonded inside the ANM case show great potential. Limitations lie in the dynamic performance of the case, which has too many resonances in the frequency range of interest. In finite element analysis, structural mechanics offers a simple means of studying effects of varying structural properties, such as thickness and shape, on structural resonances. Phase I goals are (1) to isolate the film-bonding case surface area so that case size and vibration and ANM attachment mode do not affect the transduces response and (2) to modify the film attachment area so that its dynamic response meets acoustic measurement frequency requirements. At least two case designs will be manufactured and tested to demonstrate proof-of-concept.