Diaphragm (acoustics)

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In a loudspeaker, a diaphragm (also known as the cone) is the thin, semi-rigid membrane attached to the central magnet. The magnet induces the diaphragm to vibrate, producing sound. This diaphragm is also found in headphones.

Using this in reverse converts air vibrations (sound) into electrical signals, as in several common designs of microphone.

Similarly, the eardrum uses this same principle, using a diaphragm to stimulate nerves to transmit a neural "image" of sound to the brain. In loudspeakers, cellulose fiber (paper) was the most common original material used to make the diaphragms. Paper density is modified to produce desired sound characteristics by means of refining the paper. Cellulose continues to be the most common material used in speaker cones. Today, many synthetic fibers and binders are added to enhance the acoustic properties as well as the power handling. Other materials used today are polypropylene and aluminum.