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A two-array system for localization of fish using passive acoustic data
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Resumo(s)
Passive acoustic localization methods use the time lag of a sound detected at several receivers (or at a single receiver via directed and reflected paths) to estimate the position, range or direction of a sound source. Even though the use of this method applied to vocal fish is still scarce in scientific literature, it has important potential applications, such as the elucidation of courtship and spawning behaviour of vocal fish, the estimation of the source level of vocalisations, the construction of reference libraries that associate sample vocalisations to the species that produce them, and the understanding of the role of vocal communication in social interactions such as those involved in reproductive competition. In the present text we present a low-cost system that can both estimate the positions of vocalising fish and intuitively convey the uncertainty of such estimates to the user. All the data presented in this work was obtained in a single test deployment of the recording equipment, and this dissertation was done within the context of a project with a longer temporal span. Therefore, the results presented here represent a fundamental but intermediate step towards the obtention and analysis of relevant biological data. Since studies using passive acoustic localization for fish triangulation are still scarce, and the methods employed are constrained by their specific features, it is hard to directly compare our method to the ones existing. Yet, some features in which it differs from previous work regarding fish localization by passive acoustic methods include (1) the usage of multiple arrays to overcome the limitation of point localization to distances of the same order of magnitude as the distance between the hydrophones of the array, (2) the output of a readily interpretable result that informs on both the estimated location and the associated uncertainty, (3) the modelling of the dependency structures between observed TDOAs of different pairs of hydrophones, and (4) the estimation of observed TOA variance using fish known to vocalise from fixed positions.
Descrição
Tese de mestrado, Bioestatística, Universidade de Lisboa, Faculdade de Ciências, 2021
Palavras-chave
acústica passiva localização Argyrossomus regius Hallobatrachus didactylus Estuário do Tejo Teses de mestrado - 2021