Acoustic quieting is the process of making machinery quieter by damping vibrations to prevent them from reaching the observer.
Acoustic signature is used to describe a combination of acoustic emissions of sound emitters, such as those of ships and submarines.
An acoustic torpedo is a torpedo that aims itself by listening for characteristic sounds of its target or by searching for it using sonar (acoustic homing).
A guidance system is a virtual or physical device, or a group of devices implementing a guidance process used for controlling the movement of a ship, aircraft, missile, rocket, satellite, or any other moving object.
A loudspeaker (or loud-speaker or speaker) is an electroacoustic transducer; which converts an electrical audio signal into a corresponding sound.
A microphone, colloquially nicknamed mic or mike, is a transducer that converts sound into an electrical signal.
Sonar (originally an acronym for SOund Navigation And Ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, communicate with or detect objects on or under the surface of the water, such as other vessels.
In physics, sound is a vibration that typically propagates as an audible wave of pressure, through a transmission medium such as a gas, liquid or solid.
A modern torpedo is a self-propelled weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with its target or in proximity to it.
A transducer is a device that converts energy from one form to another.
A weapon, arm or armament is any device used with intent to inflict damage or harm.