If the patient has ringing in the ear when the mouth is open, it may be due to small cerumen in the deep part of the external ear canal in the form of flakes or grains, or disorder of the jaw joint, and different treatment methods are available for different causes, as follows: 1. Small cerumen in the deep part of the external ear canal in the form of flakes or grains: When moving around, small cerumen can hit the eardrum and cause ringing in the ear. You should not pull out the ear by yourself or let others to avoid damaging the external ear canal or the eardrum. 2. Disorders of the jaw joint: Pay attention to protecting the jaw joint, try not to open your mouth wide and avoid chewing or biting hard food. Apply hot compresses to the jaw joint. If the symptoms are serious, you need to visit a dentist and get treatment under the guidance of a doctor.