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Détection robuste de signaux acoustiques de mammifères marins / Robust detection of the acoustic signals of marine mammalsDadouchi, Florian 08 October 2014 (has links)
Les océans subissent des pressions d'origine anthropique particulièrement fortes comme la surpêche, la pollution physico-chimique, et le bruit rayonné par les activités industrielles et militaires. Cette thèse se place dans un contexte de compréhension de l'impact du bruit rayonné dans les océans sur les mammifères marins. L'acoustique passive joue donc un rôle fondamental dans ce problème. Ce travail aborde la tâche de détection de signatures acoustiques de mammifères marins dans le spectrogramme. Cette tâche est difficile pour deux raisons : 1. le bruit océanique a une structure complexe (non-stationnaire, coloré), 2. les signaux de mammifères marins sont inconnus et possèdent eux aussi une structure complexe (non-stationnaires bande étroite et/ou impulsionnels). Le problème doit donc être résolu de manière locale en temps-fréquence, et ne pas faire d'hypothèse a priori sur le signal. Des détecteurs statistiques basés uniquement sur la connaissance des statistiques du bruit dans le spectrogramme existent, mais souffrent deux lacunes : 1. leurs performances en terme de probabilité de fausse alarme/ probabilité de détection se dégradent fortement à faible rapport signal à bruit, et 2. ils ne sont pas capables de séparer les signaux à bande étroite des signaux impulsionnels. Ce travail apporte des pistes de réflexion sur ces problèmes.L'originalité de ce travail de thèse repose dans la formulation d'un test d'hypothèse binaire prenant explicitement en compte l'organisation spatiale des pics temps-fréquence. Nous introduisons une méthode d'Analyse de la Densité des Fausses Alarmes (FADA) qui permet de discriminer les régions temps-fréquence abritant le signal de celles n'abritant que du bruit. Plus précisément,le nombre de fausses alarmes dans une région du plan est d'abord modélisé par une loi binomiale, puis par une loi binomiale corrélée, afin de prendre en considération la redondance du spectrogramme. Le test d'hypothèse binaire est résolu par une approche de Neyman-Pearson. Nous démontrons numériquement la pertinence de cette approche et nous la validons sur données réelles de mammifères marins disposant d'une grande variété de signaux et de conditions de bruit. En particulier, nous illustrons la capacité de FADA à discriminer efficacement le signal du bruit en milieu fortement impulsionnel. / The oceans experience heavy anthropogenic pressure due to overfishing, physico-chemical pollution, and noise radiated by industrial and military activities. This work focuses on the use of passive acoustic monitoring of the oceans, as a tool to understand the impact of radiated noise on marine ecosystems, and particularly on marine mammals. This work tackles the task of detection of acoustical signals of marine mammals using the spectrogram. This task is uneasy for two reasons : 1. the ocean noise structure is complex (non-stationary and colored) and 2. the signals of interest are unknown and also shows a complex structure (non-stationary narrow band and/or impulsive). The problem therefore must be solved locally without making a priori hypothesis on the signal. Statistical detectors only based on the local analysis of the noise spectrogram coefficients are available, making them suitable for this problem. However, these detectors suffer two disadvantages : 1. the trade-offs false alarm probability/ detection probability that are available for low signal tonoise ratio are not satisfactory and 2. the separation between narrow-band and impulsive signals is not possible. This work brings some answers to these problems.The main contribution of this work is to formulate a binary hypothesis test taking explicitly in account the spatial organization of time-frequency peaks. We introduce the False Alarm Density Analysis (FADA) framework that efficiently discriminates time-frequency regions hosting signal from the ones hosting noise only. In particular the number of false alarms in regions of the binary spectrogram is first modeled by a binomial distribution, and then by a correlated binomial distribution to take in account the spectrogram redundancy. The binary hypothesis test is solved using a Neyman-Pearson criterion.We demonstrate the relevance of this approach on simulated data and validate the FADA detector on a wide variety of real signals. In particular we show the capability of the proposed method to efficiently detect signals in highly impulsive environment.
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Sistema para monitoramento e análise de paisagens acústicas submarinas. / System for monitoring and analysing underwater acoustic landscapes.Alexander Alvarez Rosario 14 October 2015 (has links)
O Monitoramento Acústico Passivo (PAM) submarino refere-se ao uso de sistemas de escuta e gravação subaquática, com o intuito de detectar, monitorar e identificar fontes sonoras através das ondas de pressão que elas produzem. Se diz que é passivo já que tais sistemas unicamente ouvem, sem perturbam o meio ambiente acústico existente, diferentemente de ativos, como os sonares. O PAM submarino tem diversas áreas de aplicação, como em sistemas de vigilância militar, seguridade portuária, monitoramento ambiental, desenvolvimento de índices de densidade populacional de espécies, identificação de espécies, etc. Tecnologia nacional nesta área é praticamente inexistente apesar da sua importância. Neste contexto, o presente trabalho visa contribuir com o desenvolvimento de tecnologia nacional no tema através da concepção, construção e operação de equipamento autônomo de PAM e de métodos de processamento de sinais para detecção automatizada de eventos acústicos submarinos. Foi desenvolvido um equipamento, nomeado OceanPod, que possui características como baixo custo de fabrica¸c~ao, flexibilidade e facilidade de configuração e uso, voltado para a pesquisa científica, industrial e para controle ambiental. Vários protótipos desse equipamento foram construídos e utilizados em missões no mar. Essas jornadas de monitoramento permitiram iniciar a criação de um banco de dados acústico, o qual permitiu fornecer a matéria prima para o teste de detectores de eventos acústicos automatizados e em tempo real. Adicionalmente também é proposto um novo método de detecção-identificação de eventos acústicos, baseado em análise estatística da representação tempo-frequência dos sinais acústicos. Este novo método foi testado na detecção de cetáceos, presentes no banco de dados gerado pelas missões de monitoramento. / Passive Acoustic Monitoring (PAM) refers to the use of systems to listen and record underwater soundscape, in order to detect, track and identify sound sources through the pressure waves that they produce. It is said to be passive as these systems only hear, not put noise in the environment, such as sonars. Underwater PAM has various application areas, such as military surveillance systems, port security, environmental monitoring, development of population density rates of species, species identification, etc. National technology in the field is practically nonexistent despite its importance. In this context, this paper aims to contribute to the national technology development in the field by designing, building, and operating a self-contained PAM equipment, also developing signal-processing methods for automated detection of underwater acoustic events. A device, named \"OceanPod\"which has characteristics such as low manufacturing cost, flexibility and ease of setup and use, intended for scientific, industrial research and environmental control was developed. Several prototypes of the equipment were built and used in several missions at seawaters. These missions monitoring, enabled start creating an acoustic database, which provided the raw material for the automated acoustic events detectors and realtime test. Additionally, it is also proposed a new method of detecting, identifying sound events, based on statistical analysis of the time-frequency representation of the acoustic signals. This new method has been tested in the detection of cetaceans present in the database generated by missions monitoring.
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Surveillance acoustique des baleines bleues Antarctique dans l’océan Indien austral : traitement, analyse et interprétation / Acoustic monitoring of Antarctic blue whales in the Southern Indian Ocean : data processing, analysis and interpretationLeroy, Emmanuelle 25 September 2017 (has links)
La baleine bleue Antarctique, Balaenoptera musculus intermedia, est en danger critique d’extinction depuis la chasse baleinière intensive du 20e siècle. L’état de ses populations et leur écologie restent encore mal connus. En raison de l’inefficacité des observations visuelles, la surveillance par acoustique passive est privilégiée pour étudier cette espèce vocalement très active. Cette thèse porte sur l’analyse de 7 ans de surveillance acoustique passive dans l’océan Indien austral, région d’habitat et de migration particulièrement importante pour la baleine bleue Antarctique. Déployé depuis 2010 sur une aire de près de 9 000 000 km2, le réseau d’hydrophones OHASISBIO fournit une base de données acoustiques multi-site et pluri-annuelle. L’application d’un algorithme de détection automatique des vocalisations de baleines bleues Antarctique, préalablement testé et validé, a permis d’établir les patrons géographiques et saisonniers de présence de l’espèce au sein du réseau. L’analyse systématique de ces vocalisations a également permis de caractériser des variations intra- et inter-annuelles de leur fréquence, affectée par une décroissance long-terme et des modulations saisonnières. L’analyse préliminaire de signatures vocales d’autres espèces présentes dans le réseau - rorquals communs et trois populations de baleines bleues pygmées – a révélé des variations de fréquence similaires de leur vocalisation et permis d’esquisser leurs patrons géographiques et saisonniers. Enfin, deux vocalisations, jusqu’alors non décrites, aux caractéristiques semblables à celles de baleines bleues, ont été identifiées et caractérisées. / The Antarctic blue whale, Balaenoptera musculus intermedia, is currently critically endangered since the commercial whaling in the 20th century. The population recovery of this species, as well as its ecology, are still poorly known. Due to the ineffectiveness of visual observations, passive acoustics is a preferred method to monitor this highly vocal species. This dissertation presents an analysis of 7 years of passive acoustic monitoring in the southern Indian Ocean, known as a particularly important area of habitat and migration for the Antarctic blue whale. Deployed since 2010 over an area of about 9,000,000 km2, the OHASISBIO hydrophone network provides a multi-site and multi-year acoustic database. An algorithm for the automated detection of Antarctic blue whale calls, first tested and validated, has been applied to characterize the seasonal and geographic patterns of the species presence in the study area. The systematic analysis of these vocalizations also allowed to characterize intra- and inter-annual variations of their frequency, with a long-term decline and seasonal variations. A preliminary analysis of other vocal signatures recorded by the network, from 3 populations of pygmy blue whales and fin whales, highlighted similar variations of their frequencies and outlined their geographic and seasonal patterns of presence in the area. Finally, two previously undescribed vocalizations, with characteristics close to that of blue whale calls, were identified and characterized.
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Acoustique passive et peuplements benthiques avec applications aux études d'impact EMR / Passive acoustics and benthic populations with applications to MRE impact assessmentsLossent, Julie 06 February 2017 (has links)
La compréhension de la dynamique spatiale et temporelle des peuplements benthiques qu’elle soit naturelle et induite par des forçages anthropiques, nécessite de nouvelles méthodes d'observation du benthos avec des besoins affichés de haute résolution temporelle et de longues périodes de mesures. L'enregistrement et l’analyse des sons produits dans l’environnement marin donnent accès au paysage acoustique, et notamment à l’une de ses composantes biologiques la biophonie benthique. Observer les variabilités spatio-temporelles de cette biophonie benthique, afin de contribuer à l'évaluation de la structure, du fonctionnement, de l’état et des évolutions du compartiment benthique, constitue l'objectif principal de la thèse. Pour ce faire nous avons développé deux outils permettant d'évaluer la variabilité spatiale de ces émissions avec un ou plusieurs capteurs. Le premier est un descripteur de la forme des spectres des impulsions du benthos permettant de mieux caractériser la diversité de la biophonie benthique. Le second est une méthode de localisation tridimensionnelle des sources sonores benthiques et de cartographie de cette biophonie pour des échelles spatiales allant de 500 mètres jusqu’à 5 mètres. En utilisant ces deux outils, nous avons démontré la faisabilité de l'observation du benthos au travers de sa biophonie sur des sites spécifiques. Dans une partie applicative, nous nous sommes intéressés aux projets de site de production d’énergies marines renouvelables et à la compréhension et à l’observation de leurs impacts sur la faune marine. Sur un site atelier de géométrie similaire à celle d’une ferme d’éoliennes offshores, nous avons défini, réalisé et analysé une preuve de concept pour l’observabilité d’un effet de type binaire : présence ou absence de faune fixée dans une surface sentinelle de quelques mètres carré. Les travaux de thèse ont été conclus par une étude mesurant le niveau sonore rayonné par une hydrolienne en phase de production d’énergie (Paimpol-Bréhat) puis évaluant les impacts acoustiques sur trois compartiments biologiques : les mammifères marins, les poissons et les invertébrés. / Understanding the spatial and temporal dynamics of benthic populations, both natural and induced by anthropogenic pressures, requires new observation methods with high temporal resolution and long periods of measurement. The recording and analysis of sounds produced in the marine environment give access to the soundscape, and in particular to one of its biological components, the benthic biophony. Observing the spatiotemporal variability of this benthic biophony, in order to contribute to the evaluation of the structure, functioning, state and evolution of the benthic compartment, is the main objective of the thesis. To do this we have developed two tools to evaluate the spatial variability of these emissions with one sensor or more. The first is a descriptor of the shape of the spectra of the benthic snaps allowing to better characterize the diversity of benthic biophony. The second is a method of three-dimensional localization of the benthic sound sources and mapping of this biophony for spatial scales ranging from 500 meters to 5 meters. Using these two tools, we have demonstrated the feasibility of benthos monitoring through its biophony at specific sites. In an applicative part, we were interested in sites of production of marine renewable energies and the understanding and observation of their impacts on the marine fauna. On a workshop site of geometry similar to that of an offshore wind farm, we defined, realized and analyzed a proof of concept for the observability of a binary impact: presence or absence of fixed benthic fauna in a sentinel area of a few square meters. The thesis work was concluded by a study measuring the sound level radiated by a tidal current turbine in the energy production phase (Paimpol-Bréhat) and then evaluating the acoustic impacts on three biological compartments: marine mammals, fish and invertebrates.
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Soundscape dynamics in the social-ecological systems of Tierra del FuegoDante P Francomano (9738650) 14 December 2020 (has links)
<p>Human society is presently beset by an array of anthropogenic social-ecological crises that threaten the sustainability of the social-ecological systems that sustain our livelihoods. While research alone will not rectify these issues, it can help to answer key questions that must be addressed to develop effective solutions. To address such questions in a cohesive, compelling manner, social-ecological research can be bounded, structured, and distilled through innumerable organizing principles or theoretical frameworks. For this dissertation, I focused on the geographic region of Tierra del Fuego and sought to draw from the array of disciplines and methods that use sound as a lens for biological, ecological, and/or social inquiry. I also endeavored to consider various temporal, spatial, and organizational scales while investigating a selection of topics with a) specific importance in the social-ecological systems of Tierra del Fuego and b) general relevance to global social-ecological challenges. Chapter 1 provides an introduction to the dissertation, and Chapter 6 serves as a conclusion.</p><p><br></p><p> </p><p>The objective of Chapter 2, “Biogeographical and analytical implications of temporal variability in geographically diverse soundscapes”, was to provide some guidance to passive acoustic monitoring (PAM) practitioners on how to design appropriate temporal sampling schemes based on the temporal variability of the sounds one wishes to measure and the power and storage limitations of acoustic recorders. We first quantified the temporal variability of several soundscape measurements and compared that variability across sites and times of day. We also simulated a wide range of temporal sampling schemes in order to model their representativeness relative to continuous sampling.</p><p><br></p><p> </p><p>For Chapter 3, “Sentinels for sentinels: passive acoustic and camera trap monitoring of sensitive penguin populations”, we tested the utility of PAM to monitor behavior and abundance of Magellanic (<i>Spheniscus magellanicus</i>) and southern rockhopper penguins (<i>Eudyptes chrysocome</i>) at different spatial and temporal scales. We conducted <i>in situ</i> observations of the acoustic behavior of each species, and we compared acoustic metrics with penguin counts from narrowly focused camera traps and larger-extent observations of colony density. </p><p><br></p><p> </p><p>Chapter 4, “Acoustic monitoring shows invasive beavers (<i>Castor canadensis</i>) increase avian diversity in Tierra del Fuego”, is focused on impacts of the invasive North American beaver (<i>Castor canadensis</i>) on Fuegian bird communities. We sought to determine how bird communities might differ between intact riparian forests, beaver ponds, and beaver meadows created by pond drainage. We conducted PAM and classic avian point counts under each of these conditions across seasons to test for differences between impact conditions and to compare the two methodologies.</p><p><br></p><p> </p>For Chapter 5, “Human-nature connection and soundscape perception: insights from Tierra del Fuego, Argentina”, we evaluated the relationship between soundscape perception and nature relatedness by conducting surveys and soliciting responses to soundscape audio prompts. We also examined the potential for any demographic influences on nature relatedness or soundscape perception in the context of local social tensions.
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