Speaker

A loudspeaker, speaker, or speaker system is an electromechanical transducer that converts an electrical signal to sound. The term loudspeaker can refer to individual transducer devices (otherwise known as drivers), or to complete systems consisting of an enclosure incorporating one or more drivers and electrical filter components. Loudspeakers, just as with other electro-acoustic transducers, are the most variable elements in an audio system and are responsible for the greatest degree of audible differences between sound systems.
To adequately reproduce a wide range of frequencies, most loudspeaker systems require more than one driver, particularly for high sound pressure level or high accuracy applications. Individual drivers are used to cover different frequency ranges. The drivers are named subwoofers (very low frequencies), woofers (low frequencies), mid-range speakers (middle frequencies), tweeters (high frequencies) and sometimes supertweeters which are drivers optimized for higher frequencies than a normal tweeter.

The terms for different speaker drivers differ depending on the application. In 2-way loudspeakers, there is usually no driver called "mid-range". Home stereos use the designation "tweeter" for high frequencies whereas professional audio systems for concerts typically designate all types of high frequency drivers as "HF" or "highs" or "horns".

When multiple drivers are used in a system, a "filter network", called a crossover, is used to separate the incoming signal into different frequency bands appropriate for each driver. A loudspeaker system with n separate frequency bands is described as "n-way speakers": a 2-way system will have woofer and tweeter speakers; a 3-way system is either a combination of woofer, mid-range and tweeter or subwoofer, woofer and tweeter.