Design And Implementation Of Biomimetic Small Microphone Array Inspired By The Ears Of Ormia Ochracea

The sound source localization technology is very useful both in the military and civil fields.Traditionally,a microphone array consists of at least two individual probes and the ITD is the only available directional cue which is proportional to the distance of them.As a result,it has to keep enough separation to ensure reliable measurement of phase information.The localization performance relies heavily on the dimension of the array.This disadvantage largely restricts the applications of microphone array.Sound source localization is one of the most important functions of the auditory system in any hearing animals.The main acoustic directional cues available for animalsare interaural time differences and interaural intensity differences.They are generated by the distance between ears and the significant diffractive effect due to the head,respectively.Because larger ITD and IID available for animals with huge body size,they have an inherent advantage over those with small size.Sharing the same principle with the microphone array,they should keep great distance between two ears for precise localization.However,the fly Ormia ochracea can precisely determine the direction of sound source via its special coupled ears even though its size is extremely small.In this thesis,the principle of Ormia ochracea's localization ability is further studied and its model of ears is investigated in mechanics,electrics and acoustics,respectively.An primary experiment is implemented to explore the direct realization of the ear model.In this experiment,two plastic thin diaphragms are used as acoustic receiver and are coupled by a metal strip.The vibration state is measured by laser vibration meter.Based on this exploration,an equivalent analog circuit is designed to mimic the coupled ears of the fly Ormia ochracea for sound source localization.The output signals from space-closed microphone array are coupled and its response offers obvious amplitude difference and phase difference.Besides,the parameters of the coupled circuit can be adjusted to get high sensitivity to the sound incident angle.The experiment results are in good agreement with the theory.This could greatly miniaturize the traditional microphone array and reduce the burden of computation.