For some, the electrical concepts behind speakers may seem too complex to comprehend, but it actually uses a fairly simple concept involving vibrations of air molecules. In order to make these vibrations, a cone is set up like the one pictured below. When an alternating current is provided through the coil, it creates an electromagnetic field that attracts and repels from the magnet positioned opposite of the coil. This then “pumps” the air through the cone, vibrating at certain frequencies depending on the current used by the coil, thus creating sound.
Because an alternating current is used to power the speaker, we can use that same current to power a set of LEDs. This will then create an effect that pulses the LEDs at a similar frequency and brightness related to the sound coming out of the speakers, creating a simple and beautiful light show.