Electric speakers are mainly used in the field of relay rather than the speaker

The speaker is also called "horn"". Is a very commonly used electroacoustic transducing devices in electrical and electronic equipment, sound in can see it. The speaker is one of the most weak parts in the audio equipment, and it is one of the most important parts for the sound effect. Although it is such a simple device, its development is not an overnight, but after a long research and many people's efforts, gradually moving towards maturity and progress. The invention of the speaker is to let "recordings", but despite the efforts of many scientists, this goal has not yet been fully achieved, but is different vocal style, using different manufacturing methods and materials, thus the horn of letting a hundred flowers blossom become sound in the world the most brilliant of a garden. Speakers are divided into built in speakers and external speakers. External speakers that are generally refers to the speakers, built-in speakers is the MP4 player with a built-in speaker. Kinds of speakers and according to the energy exchanging principle can be divided into electric (i.e. moving coil type) and electrostatic (capacitive) and electromagnetic (Reed) and piezoelectric (i.e. crystal type) of several. 

The W. Siemens Ernst (Siemens Halske) is the prototype of the speaker in January 20, 1874. The speaker is a sound coil in a magnetic field in which the supporting system is in a magnetic field so that the vibration system can be kept in an axial direction. At that time was mainly used for the relay rather than the speaker. December 14, 1877, Siemens for horn patent, on top of a moving coil attached to a parchment as sound radiator and parchment paper can be made of exponential type cone shape, which is the first gramophone age horn real