A loudspeaker (or "speaker", or in the early days of radio "loud-speaker") is an electroacoustic transducer that produces sound in response to an electrical audio signal input. The most common form of loudspeaker uses a paper cone which is vibrated by an attached voice coil electromagnet between the poles of a permanent magnet, but many other types exist.
To adequately reproduce a wide range of frequencies, most loudspeaker systems employ more than one driver, particularly for higher sound pressure level or maximum accuracy. Individual drivers are used to reproduce different frequency ranges. The drivers are named subwoofers (for very low frequencies); woofers (low frequencies); mid-range speakers (middle frequencies); tweeters (high frequencies); and sometimes supertweeters, optimized for the highest audible frequencies.