Inside a Muffler
Located inside the muffler is a set of tubes. These tubes are designed to produce reflected waves that interfere with each other or cancel each other out. Look inside the muffler:
Exhaust gas and sound waves enter through the center tube. They bounce off the back wall of the muffler and are reflected through a hole into the body of the muffler. They pass through a set of holes into another chamber where they rotate and exit the last pipe and exit the muffler.
A chamber called a resonator is connected to the first chamber through a hole. The resonator contains a specific volume of air and has a specific length that is calculated to produce a wave that cancels the sound of a particular frequency. How did this happen? Let's take a closer look...