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Saved by Omer Asmat
on April 21, 2011 at 9:22:30 am





Table of contents:


    2.What is a loudspeaker?







Invention of the first Loudspeaker:


In 1867, Alexander Graham Bell constructed the first ever electrical speaker device for the purpose of building a telephone. In 1877, Ernst Siemens improved upon Bell's invention and invented a more advanced electrical loudspeaker. During the period of 1867 to 1891, physicists such as Nikola Tesla  were working upon improving this idea of the loudspeaker. The research of these three physicists 'sparked' the development of the modern-era loudspeaker. For example, Tesla's work and research helped develop the modern AC electric power systems which contributed to the development of the loudspeaker.



Alexander Graham Bell,  Nikola Tesla and Ernst Siemens (left to right) were key individuals who contributed to the development of the modern speaker.


Further Improvements:

In 1898, Horace Short used the design of the loudspeaker which was driven through compressed air. These designs however proved to have flaws such as poor sound quality and inability to produce sounds at a low volume. At this time, other scientists such as Oliver Lodge were experimenting with the modern design of moving coil. In 1924, Chester W. Rice and Edward Kellogg patended the design of the moving coil principle. However, the difference between Lodge's design and Rice and Kellog's design was the adjustment of certain mechanical parameters. The first ever ribbon loudspeaker was invented by Walter H. Schottky.


What is a loudspeaker?


Brief Description:

A loudspeaker is a device which converts electricity into sound which is amplified through a device. Commonly used loudspeakers are radios and stereo systems. There are many different types of loudspeakers and they all are different in terms of producing sound frequency. A loudspeaker can also be referred to transducer which means that it converts a certain type of energy into another. In this case a loudspeaker converts electrical energy into sound energy.


A typical stereo system. 



The most common speaker is the dynamic speaker. It consists of a frame, permanent magnet, soft iron core, voice coil, and cone. The frame supports the cone and permanent magnet assembly. The voice coil consists of an insulated wire wound around a plastic bobbin. One end of the bobbin is attached to the cone and the body of the bobbin slides over the soft iron core.




Many common types of drivers today are made from lightweight diaphragm, or cone which is then connected to a rigid basket type frame. Basically an electric signal is applied to the voice coil, in which a magnetic field is created by running current through it. A mechanical force is generated by the interaction of the coil and the driver's mechanical system causing the coil to move back and forth, thereby reproducing sound. The field around the coil begins to act like a magnetic field in a permanent magnet, thus it has a polar orientation, in simple terms a North and South end. However, the orientations are able to be altered. If the flow of the current is reversed, the north and south ends of the magnet switch. The amplifier constantly switches the electrical signal, causing the fluctuation between a negative and positive charge in the red wire. An electron always flow the same way between negatively charged particles and positively charged particles, the current goes through the speaker one way, but then switches directions and flows the other way. This alternating current causes the polar orientation of the electromagnet to alternate many times in a second.




"How Speakers Work." How Stuff Works. N.p., n.d. Web. 19 Apr. 2011. <electronics.howstuffworks.com/speaker5.htm >.


"Loudspeaker." Wikipedia. N.p., n.d. Web. 18 Apr. 2011. <en.wikipedia.org/wiki/Loudspeaker >.


"Stereo Speaker: How Products are Made." eNotes - Literature Study Guides, Lesson Plans, and More.. N.p., n.d. Web. 21 Apr. 2011. <http://www.enotes.com/how-products-encyclopedia/stereo-speaker>.


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