When was the loudspeaker invented?
In December 14, 1877, Siemens filed a patent in a horn, the voice coil is moved above the attachment of a parchment as sound radiator, parchment paper can be made into exponential cone shape, this is the first real horn gramophone age.
The loudspeaker was invented by lightning in 1950. Mainly used for teaching, guides, outdoor activities.
