Loudspeaker

A loudspeaker is an electroacoustic transducer that converts an electrical audio signal into sound waves by moving a diaphragm or other radiating surface.

Voice coil: A coil of wire that moves within a magnetic field when electrical current passes through it. Current through the coil creates the force that drives many loudspeaker diaphragms.
Audio signal: A time-varying representation of sound, carried electrically, digitally, or acoustically. It is the input whose changing voltage drives the loudspeaker.
Woofer: A loudspeaker driver designed primarily to reproduce low-frequency sound. It handles bass frequencies in many multiway loudspeaker systems.
Electrostatic loudspeaker: A loudspeaker that moves a charged diaphragm using electrostatic forces. It replaces the conventional voice-coil motor with an electric-field-driven diaphragm.
Alexander Graham Bell: A Scottish-born inventor and educator associated with the development of the telephone. Bell's telephone work included early devices that converted electrical signals into sound.
Permanent-magnet loudspeaker: A loudspeaker design in which a permanent magnet and voice coil produce diaphragm motion. This common motor structure turns the audio signal into mechanical movement.
Sound pressure: The local deviation of air pressure caused by a sound wave. The loudspeaker's radiated sound is measured as pressure variation in air.
Tweeter: A loudspeaker driver designed primarily to reproduce high-frequency sound. It reproduces treble frequencies that a woofer handles poorly.
Ribbon loudspeaker: A loudspeaker that drives a thin conductive ribbon in a magnetic field. Its radiating conductor is itself a lightweight diaphragm rather than a separate cone and coil.
Ernst Werner von Siemens: A German inventor and industrialist who described an electromagnetic transducer principle in 1874. His moving-coil principle became foundational to dynamic loudspeaker design.

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