I don't know, but you really should see a doctor, specifically an ear, nose , and throat doctor (otolaryngologist). One possibility is that you have a middle ear infection that's resulted in your ears having fluid behind the ear drums. The condition is called serous otitis media. There's a simple, painless test that can be used to diagnose this called impedance audiometry.
If you have this problem, it's very, very important that you get help, not only because of your hearing but because an infection like this can do permanent damage.
Tell your parents.