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As you all know, sound is made up of vibrations. There are areas of rarefactions and compressions. The waves of changing air pressure are perceived by our ears, and interpreted. Now, I wondered how these sounds were recorded onto vinyl records, and played back as a faithful recreation of the original sound. To do this, I researched the workings of Thomas Edison, the inventor of the phonograph. Originally, sound was collected by a horn, similar to the way the human ear works. This horn was attached to a diaphragm, which is a thin membrane (like a drum skin). Therefore, when sound passed through the horn, the diaphragm would vibrate at a similar rate of the sound vibrations. This diaphragm was attached to a stylus, or small metal needle. The stylus was placed against a cylinder that was either covered in wax, or a thin layer of tin foil. When sound was collected by the horn, the diaphragm would vibrate, and the needle would move up and down against the wax cylinder. This wax-covered cylinder was rotated at a constant rate of speed, so that the needle would cut a path, or a groove across the surface of the cylinder. The cuts in the groove form a replica of sound waves.
By setting the stylus into the groove, and rotating the cylinder at the same rate of speed, as when the recording was made, the stylus in turn would vibrate the diaphragm, pushing the sound waves back through the horn, where they would be amplified, and the sound would become audible. Although it is a relatively simple concept, the timing and the motion of the cylinder must be played back accurately for this phonograph to work.

Moving on to modern records, we now have the technology whereby we can record records in stereo, with a left and right channel for a more realistic sound. Originally when records were recorded, the stylus moved horizontally. Now we can recreate stereo by tracking the sound waves both vertically and horizontally within the groove of record....