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A speaker is an electronic device used to transform varying electric current into audible sound. It usually consists of a speaker cone, most often made of plastic or cardboard, which is moved by magnetic forces induced by the electromagnet to which the input signal is directed.

An active speaker contains a built-in amplifier to process low voltage sound signals, while a passive speaker requires an external amplifier.

The most important properties of a speaker are its impedance (expressed in ohms), power handling capability (in watts), and its frequency output range, which determines the range of sounds the speaker is able to produce.

See also: loudspeaker

The "Speaker" (more formally, Speaker of the House) is the presiding officer in many legislative bodies, including the United States House of Representatives and the House of Commons in Westminster System parliaments. See Speaker of the House of Commons.