Acoustic warfare utilizes acoustic energy underwater to identify and intercept targets and to protect friendly shipping. Specialists in acoustic warfare work with various acoustic sensors and sonar equipment, typically on submarines and ships. Effective utilization of the underwater acoustic spectrum is an important aspect of modern warfare, allowing nations to protect themselves from enemy submarines and shipping and ensuring that countries have control over their territorial waters.
There are several different aspects to acoustic warfare. In the first sense, technicians use acoustic information to gather data. For example, a technician on a submarine might identify an unusual sound, and suggest that the staff investigate it to determine whether or not it is a threat. A skilled technician can figure out whether an animal or a device is causing a sound, and in some cases he or she may be able to determine what kind of device is causing the sound; a friendly fishing boat, for example, as opposed to an enemy submarine.
Technicians can also use active emission of acoustic energy to jam enemy electronics systems as a countermeasure. Many submarines have equipment which is designed to mask their distinctive acoustic signatures, allowing them to move silently or under the cover of an acoustic shield of some kind which obscures their characteristic sounds. These countermeasures are usually designed in such a way that they block the enemy's usage of the acoustic spectrum without interfering with friendly ships and submarines.
The concept of acoustic warfare started to come into its own in the Second World War, when the Germans utilized U-Boats to devastating effect against Allied convoys and shipping. The Germans realized that the unique conductive properties of water could be utilized as a powerful military tool, and also that they needed to be aware of their own acoustic emissions to ensure that they could move stealthily through dangerous territory. After the Second World War, several nations invested in the development of submarine fleets and supporting tools for acoustic warfare.
Someone who wishes to specialize in acoustic warfare is typically offered unique training. He or she may have to take special exams to qualify, since the technician will be entrusted with delicate and complex equipment. Technicians learn about a wide array of acoustic warfare measures and countermeasures which are routinely used as part of their work, and they are also given ample field experience which helps them prepare for a range of situations.