THX Sound

I have no idea where my son got the idea that THX sound system in the movie is freaking scary. He just freaks out every time his dad plays a movie that has THX sound in it. He started to get scared when he was only two years old and until now, he asks every time Daddy is playing a movie if there is THX in it. My husband is trying to teach our son to get over it by playing those movies that has THX but i find it not a good idea because our son gets nightmares during at night. It's like torturing him when he sees those movies that has THX. I am hoping that he will get over it soon and he won't be scared the THX sound anymore so he will enjoy to watch those movies instead. There's a lot of movies that has THX sound and our poor boy is not going to like it soon as he sees THX printed on the back of the movie case. He makes sure that the movie he is going to watch doesn't have THX sound by looking at the back of the movie case. He maybe get over it soon but i just don't know when.