Deep-sea biologists may use acoustic technologies in their work. One of the best systems for imaging large areas of the ocean floor is side scan sonar. Side scan sonar technology provides high resolution, almost photographic quality imagery of the seafloor. The technology uses a specially shaped acoustic beam, which pulses out 90 degrees from the path that it is towed, and also out to each side. Each pulse provides a detailed image of a narrow strip directly below and to either side of the instrument. The topography of the ocean floor and underwater objects reflect sound energy back to hydrophones on the towfish. These reflections are amplified, processed, and displayed as images. Multibeam sonar systems produce many beams of sound at the same time to cover a large fan-shaped area of the ocean floor, which produces high-resolution bathymetry data throughout a survey area. Since they acquire dense sounding data both along the ship’s track and between the track lines, they can provide 100% coverage of the seafloor. Multibeam sonar is used to locate topographical features on the seafloor such as sediment ridges, rock outcrops, shipwrecks, and underwater cables.
Cable-linked seafloor observatories allow scientists to study and monitor the deep ocean. Cabled ocean observatories include a vast, integrated network of oceanographic sensors that measure physical, chemical, geological, and biological variables, including underwater acoustics, in the ocean and seafloor. Cabled ocean observatories include the ALOHA Observatory (ACO) 100 km (60 mi) north of Oahu. In addition to ocean sounds, the ALOHA Observatory continually obtains observations of temperature, salinity, and ocean currents, which are shared in real time with the oceanographic community and the general public. The Regional Scales Nodes project, will consist of 900 km of cable across the Juan de Fuca tectonic plate in the Pacific Ocean to investigate processes such as ocean acidification, seismic activity, spreading centers, habitat characterization, and coastal upwelling. Listen to the Deep Ocean Environment (LIDO) is an international passive acoustic monitoring project maintained by the Laboratory of Applied Bioacoustics (LAB) of the Technical University of Catalonia. The project involves processing real-time data streams from cabled deep-sea platforms and moored stations across the globe to detect, classify, and localize natural, biological, and anthropogenic sounds.