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.