Even if we don't realize it, speakers are all around us. Our TVs, cellphones, headphones, radios, and computers all use speakers of different types. Although there are many different sizes, shapes, prices, and sounds to speakers, they all use the same underlying system, which relies on electricity and magnetism.

How a Speaker Works

On a basic level, a speaker is the opposite of a microphone. It takes an electric signal and transforms it into sound waves that humans can hear. However, the underlying technology is more complicated than this. There are three main parts of a speaker: the diaphragm, the voice coil, and the magnet.

The diaphragm is a cone shaped structure. The cone is a flexible sheet of paper, metal, or plastic attached to the wide end of the diaphragm. The suspension (also known as surround) is a flexible rim that allows the cone to move. It in turn is attached to the frame of the diaphragm. The narrow end of the diaphragm is attached to the the voice coil by the spider.

The voice coil is the electromagnetic part of the speaker. The voice coil is a tight coil of wire hooked up the the speaker's power source. Alternating current electricity is run through the voice coil, causing it to constantly switch polarity.

The magnet is a permanent magnet that sits beneath the voice coil. The side that is facing the voice coil has one unchanging pole. Since the voice coil keeps changing polarity, it is constantly being attracted to and repelled from the magnet.

The voice coil's back and forth movement causes the diaphragm to vibrate. This vibration translates electrical signals into sound waves which humans can perceive.