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Passive acoustic monitoring is a widely used technique in bioacoustics to study marine life. Passive acoustic monitoring involves placing the necessary recording tools at sea and monitoring the different vocals of sea life. The tools used to record the acoustics can be used to map-out several habitats of marine species over a long period of time. The data collected is used to identify the distribution of marine species, their movement, and their migration habits. The recordings can also be used to identify unknown species living deep in the sea. Comparisons between current-and-previous data of sounds and spatial distribution of data can help scientists identify unknown species and their importance in the aquatic ecosystem.


Challenges of passive acoustic monitoring


The data collected from marine calls is massive. There isn’t an efficient way to analyze the data into useful information and reports. With thousands of calls recorded, users of passive acoustic monitoring need to spend many hours interpreting the collected data. There is also a challenge in eliminating other sounds that are not relevant to marine calls. For example, The Journal of the Acoustical Society of America did a study on passive acoustic monitoring and they collected a lot of data during a span of one year. It took using a rule-based algorithm and two unsupervised learning algorithms to analyze all the data.


Uses of passive acoustic monitoring      


According to the National Oceanic and Atmospheric Administration, passive acoustic monitoring is used to understand communication between marine animals. There are many sounds that are produced by different species underwater. The responses that other sea life show after certain vocals are produced helps scientists how sea animals communicate.


The sounds produced can be used to understand the distribution and habitats of sea animals; for example, density of a habitat can be identified by the number of sounds produced by sea life. The devices used can record sound within 10m to 25m range and are responsive between the frequencies of 800Hz up to 2 kHz.


Bioacoustic studies use vocal in conjunction with visual observations to map out the areas where habitats are located. The habitat can be measured in terms of length, width, and even depth. Mapping is not confined to the areas that can be seen but also the areas deep within the sea. They also monitor how species are distributed in the sea, as well as their movements from one area to another.

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