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Title
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Distributed microphone arrays for passive acoustic localization across spatial and temporal scales
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Author
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Abstract
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| To an electronics engineer, the world around us is quantified using sensors. These sensors fall into two main categories: passive, where existing phenomena are measured, and active, where the system emits a signal itself. Active sensing modalities include sonar, which emits sound and records echoes with microphones to sense objects, GPS that triangulates receiver position using time delays from satellite signals, and MRI, utilizing strong magnetic fields to visualize the interior of a human body. In contrast, passive sensing modalities require no signal emission and instead rely only on existing phenomena for measurement. Examples include cameras, microphones, seismometers, and magnetic compasses. Passive acoustic localization refers to a set of measurement techniques utilizing pre-existing audio to localize and analyze the audio source. Typically, a microphone array is employed. Spatial variation in the microphone locations, i.e. two microphones cannot be placed at the same position, result in slight differences in the recorded audio at each microphone. These differences can manifest as timing disparities, attributed to varying sound travel distances to each microphone, or differences in intensity due do microphone position and the radiation pattern of the sound source, i.e. the difference in audio strength depending on the angle. Analyzing these differences allows deducing properties of the sound source, including position, path, point of acoustic focus, radiation pattern, etc. The main advantage of passive localization is that it can be deployed unobtrusively, i.e. without disturbing the sound emitting object that is being studied. In biological applications, this means there is no need to capture the animal to attach sensors to it. In industry, this means no machines have to be brought down to be retrofitted with sensors. In public infrastructure, this means no major infrastructure works and downtime are needed. The main advantage of acoustic localization is that it can be applied to any animal, object, etc. that emits sound and only these already occurring sounds are needed to perform the analysis. The main reason for us to study passive acoustic localization is that it enables us to study animals in their natural environment. Passive acoustic localization allows us to study bats without disturbing their natural behavior. We can just sit by areas that are frequented by bats, set up our array and investigate what makes them the aerial acrobats that they are. |
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Language
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English
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Publication
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Antwerpen
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University of Antwerp, Faculty of Applied Engineering
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2024
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DOI
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10.63028/10067/2062120151162165141
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Volume/pages
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xii, 130 p.
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Note
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Steckel, J. [Supervisor]
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Daems, W. [Supervisor]
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Full text (open access)
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