The first loud speaker was patented by Ernst Siemens in 1877 in German. A loudspeaker is a device, which converts electric signals into audible sound with the help of vibrating conical diaphragm. These devices use electric and mechanical principles to convert an electrical signal into sound waves. This device usually contains a stiff paper cone, a circular magnet and a coil of thin copper wire. These devices are used in mobile phones, radios, television sets and electric musical instruments. Some of the speakers are designed to produce high-pitched sounds. Such speakers are known as tweeters. Some of the loudspeakers, such as woofers and subwoofers, are designed to produce low-pitched sounds. These advanced devices have become extremely popular because of their excellent designs and high quality. http://amplify.com/u/a1fy9a