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The Science Behind: Speakers

Imagine you just want to go to sleep, but ear-splitting, deafening music causes your house to vibrate like a magnitude 10 earthquake is shaking the ground. AND IT’S COUNTRY MUSIC! WHO LISTENS TO COUNTRY MUSIC!?!? And how does this seemingly small device manage to produce so many different blaring sounds?

The four main parts of speakers are the voice coil, the cone, the electrical signals, and the permanent magnet. The basis of how speakers work is that they convert electrical energy into mechanical energy or motion.

When music is played on a speaker, an electrical current identical to the music soundwave but more powerful is produced by your stereo/amplifier. The voltage from the electrical current then starts to rise, and the current flows through the voice coil (the golden coil in the center). This creates a magnetic field around the voice coil, albeit a small one. The field starts to react with the other magnetic field created by the permanent magnet.

Since the audio signal in the form of an electrical current is constantly moving up and down, the voice coil alternates between positive to negative charges. This causes the voice coil to get retracted and pushed again and again. The cone moves along with the voice coil, creating pressure waves in the air that we perceive as sound. This whole process is just for one musical signal, though. This process happens many, many times to create a song.


  • The cone can move THOUSANDS of times every second in order to create sound.

  • There is a multitude of sounds that are IMPOSSIBLE for an ordinary speaker to produce. Some examples are very high or low frequency sounds that are beyond their range. A $2,000 speaker on Best Buy can only produce sounds up to 22 kilohertz, which most humans can’t hear. (I say most because there are exceptions, such as certain settings or individuals.) Another sound that speakers cannot accurately reproduce is the square wave, a sound wave in the shape of a square. The reason behind this is because it gives no time for the sound to rebound on the cone.

That’s all for today! Now you know how your neighbor’s speaker manages to annoy you all night!






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