loudspeaker

A loudspeaker is an electromechanical transducer that converts electrical audio signals into audible sound. An amplifier drives a diaphragm to move air, creating pressure waves. In a typical system, a driver sits in an enclosure and may be paired with crossovers and multiple drivers to cover a range of frequencies.

Most modern loudspeakers use dynamic, moving-coil drivers. A current in a voice coil interacting with a permanent magnet moves a cone. The moving-coil design became standard in the 1920s, with early work credited to Chester W. Rice and Edward W. Kellogg at Bell Labs.

Key components include the diaphragm (cone), voice coil, magnet assembly, suspension (spider and surround), and a supporting basket within an enclosure. The coil’s motion in the magnetic field drives the diaphragm, which radiates sound. The enclosure influences bass response and reduces unwanted resonances.

Other driver types include electrostatic (flat diaphragms between stators), planar-magnetic, and horn-loaded designs. In practice, many systems use multiple drivers—woofers, mids, and tweeters—arranged in one or more enclosures to reproduce different frequency bands.

Performance is described by frequency response, sensitivity, impedance, and power handling. Common home speakers use 4–8 ohms nominal impedance and sensitivities around 87–95 dB per watt at one meter. Enclosures may be sealed or ported (bass-reflex); additional designs include transmission lines and horns. Crossovers separate the signal to drivers; active systems use built-in amplification.

Loudspeakers are used in home audio, professional sound reinforcement, cinema, and automotive applications. Design choices balance efficiency, size, distortion, and tonal neutrality, while room acoustics and placement significantly influence perceived performance.