The Eustachian tubes are small passages that connect the middle ear to the back of the throat. Their main function is to equalize air pressure on both sides of the eardrum, which is essential for proper hearing. These tubes help drain fluid from the middle ear and protect it from infections. When you swallow or yawn, the Eustachian tubes open to allow air to flow in or out, balancing pressure. If they become blocked due to allergies, colds, or sinus infections, it can lead to discomfort, hearing issues, or even ear infections.