Acoustic intelligence, known as ACINT in military jargon, is intelligence gathered through analysis of auditory phenomena. The term is generally used specifically in reference to undersea intelligence gathered by submarines, sensors, and passing ships. ACINT has been used in military applications since the 1960s, and many nations have extremely well-developed acoustic intelligence programs.
This type of intelligence is part of a larger family of types of intelligence known as Measurement and Signals Intelligence (MASINT). MASINT involves the analysis of all sorts of data to gather information about a wide variety of situations and environments. In addition to acoustic intelligence, MASINT includes radar, infrared, laser, spectroscopic, and nuclear intelligence, among many others. People who work in this field may work in the field or in the lab, with lab workers using advanced scientific techniques to extract useful information from the data they gather.
Thanks to the common desire to be ahead of other countries, many militaries have highly advanced equipment at their disposal for use in ACINT research and development. Researchers in this field may also work on developing new techniques and equipment to ensure that they remain at the head of the pack.
This form of intelligence involves listening to the sea and categorizing the sounds which are heard. Experts in acoustic intelligence can differentiate between natural sounds, such as movements of the ocean floor and passing animals, and human-generated sounds like boats, submarines, and so forth. Acoustic intelligence also involves the study of how sounds move in the ocean, ranging from radar pings to the groaning of ship's hulls.
The body of knowledge accumulated in this field allows technicians to distinguish between different types of sounds when they work on board ships, filtering out the characteristic acoustic signatures of things which are viewed as non-threatening. Modern equipment can even perform this filtering automatically, allowing technicians to focus on more ambiguous noises which could be a source of concern. Acoustic intelligence is also used to monitor ocean health, with researchers listening for the sounds which define a region of the ocean, and reporting changes which suggest problems.
Oceans are noisy places. Passing creatures create cavitation waves which leave a distinctive signature, and they may also emit various sounds and generate noise as they eat, scrape along the ocean floor, and engage in various other activities. Oceans also generate noises of geologic origin, like rumbling from undersea volcanoes. Learning to distinguish these noises is important, as is learning to identify noises which do pose a threat, like the whispering engines of advanced submarines, or the sounds of incoming torpedoes.