Acoustic homing is a system which uses the acoustic signature (

sound In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by ...

) of a target to guide a moving object, such as a

torpedo A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, and with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, ...

. Acoustic homing can be either passive or active in nature. Using passive homing, the system is designed to move either toward or away from a sound, and may also be designed to move only toward certain types of sounds to the exclusion of others, while active homing makes use of active

sonar Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances (ranging), communicate with or detect objects on o ...

. The system emits a sound pulse that reflects off objects and then back to the system, where the system processes the echos to determine the proper response.

Method

An object can be equipped with two or more acoustic transducers, which function as speakers and microphones. If a transducer receives a sound louder than that received by the other transducer, the object turns in the transducer's direction. If the object is to manoeuvre in three-dimensional space, more than two transducers are needed. Typically, more than three transducers are used, and arrays of over 100 are not unknown. A large number of transducers allows for more accurate steering.

Uses

Acoustic homing is useful in

weapons A weapon, arm or armament is any implement or device that can be used to deter, threaten, inflict physical damage, harm, or kill. Weapons are used to increase the efficacy and efficiency of activities such as hunting, crime, law enforcement, s ...

, specifically acoustic torpedoes. Torpedoes can be steered toward targeted ships using acoustic homing. Torpedos axb01

Method

Uses

See also