Chewing loudly

I just finished watching an episode of How I Met Your Mother and a character on there is a "loud chewer." This character chews with her mouth closed but the chewing is still loud. I have been told that I chew loudly, and I chew with my mouth closed as well. What I don't get is, how would I chew quietly? Doesn't the sound depend on what you're eating? How can I control the volume of the crunch? Can somebody help provide some answers for me?