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Video: Loudspeaker (the invention)

Almost all of the loudspeakers manufactured today were inspired by Ernst Werner Von Siemens’ invention,  which, patented in 1877, introduced the principle of a mobile electrical coil.

The physical principle which enables this wire coil to be set in motion is magnetic force.

It had been  known for a long time, then, that a conducting wire placed in a region where a magnetic field was acting, is subject to  a force if current is flowing through it.

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This force is proportional to the current. And, to increase its intensity, the wire was wound around itself to form a coil.

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But what was new at that time was the idea of applying this principle to emit sound by attaching a flexible membrane to the coil.

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Ernst Werner Von Siemens’ loudspeaker is a true technical feat when one knows that the sounds audible to a human ear are between 20 Hz and 20kHz.

The device thus had to be capable of producing mechanical vibrations reaching several thousands of oscillations per second.