The loudspeaker is a kind of electroacoustic transducer; A device that converts electrical audio signals into corresponding sounds. The first rough loudspeakers were invented in the development of the telephone system at the end of the 19th century, but the vacuum tube electronic amplifier that began around 1912 proved that loudspeakers were really practical. By the 1920s, they were used in radios, gramophones, public address systems, and theater sound systems to talk about films.

The most popular loudspeakers today is the dynamic loudspeaker, which was invented by Edward W. Kellogg and Chester W. Rice in 1925. The working principle of the dynamic loudspeaker is the same as that of a dynamic microphone, but on the contrary, it makes sound through electrical signals. When AC audio signal input is applied through the voice coil, the voice coil is a coil suspended in the circular gap between the two poles of the permanent magnet. Due to Faraday's induction law, the coil is forced to move back and forth rapidly, resulting in the diaphragm (usually conical) connected to the coil moving back and forth, pushing the air to produce sound waves. In addition to this most common method, several alternative technologies can be used to convert electrical signals into sound.

When high-fidelity reproduction of sound is required, multiple loud speakers

can be used, each of which reproduces a portion of the audible frequency range. Miniature speakers can be found in radio and television receivers and many forms of music players. Large loudspeaker systems are used for sound reinforcement in music, theatres, concerts, and public address systems.

Speakers are usually installed in an enclosure, which is usually a rectangular or square box made of wood or plastic.