Diaphragm (acoustics)

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In a loudspeaker, a diaphragm (also know 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 paper was the most common material used to make the diaphragms. Paper density was used to produce desired sound characteristics. Paper cones have largely been replaced by other materials such as polypropylene, glass fiber, and graphic fiber.