Spatio-Temporal Characterization of Bio-acoustic Scatterers in Complex Media

Abstract

Award number: N000141110259 LONG TERM GOALSTo develop a numerically efficient methodology for modeling the acoustic response of large aggregate of biological scatterers to parameterize acoustic models for long-range SONAR measurements OBJECTIVECharacterization of biologically-induced ocean reverberation features is key to effectively parameterize acoustic models and thus ultimately improve the detection performance of long-range SONAR systems. In particular, scattering from fish schools can significantly contribute to volume reverberation in the open ocean measured by mid-frequencies tactical SONAR (1kHz-10kHz), especially if the resonance frequencies of the fish' air-filled swim bladder is excited. Furthermore, multiple scattering effects from the incident acoustic wave and the collective arrangement of fish lead to complicated frequency response functions. The bio-acoustics properties of the fish body and geometry can also contribute to the scattering response and can be incorporated into an accurate scattering model. The objective of this research is to characterize the relevant spatial and temporal scales of bio-acoustic scatterers generating ocean reverberation to effectively parameterize acoustic models and improve the detection performance of long-range SONAR systems. To do so, we developed an efficient modeling technique to predict the scattered fields from large fish schools (which can cause especially high falsealarm rate for mid-frequency SONAR systems.), which readily account for the fish acoustic properties, school's spatial configuration and multiple scattering effects.