Strong hearing on one side and weak hearing on the other side may be caused by diseases of the external ear canal, middle ear diseases, sudden deafness and other diseases. You need to go to the ENT department of the hospital as soon as possible for examination to clarify the cause of the disease before further treatment. 1. Diseases of the external auditory canal: such as eczema of the external auditory canal, boils of the external auditory canal, otitis externa, fungal diseases of the external auditory canal, cerumen embolism, etc., if unilateral ear onset, there may be a strong hearing on one side of the ear and a weak hearing on the other side, and may be accompanied by ear blockage, ear pus, ear pain, itchy ears and other symptoms, you need to be examined by the otorhinolaryngologist to clarify the nature of the disease, and then comply with the doctor’s prescription of drug treatment. 2. Middle ear diseases: such as otitis media, tympanic membrane perforation. Mostly occurs in one side of the ear, there may be ear stuffiness, ear blockage, ear pain, ear pus, hearing loss and other symptoms, need to be guided by the doctor to further otoscopy to clarify the diagnosis and further treatment. 3. Sudden deafness: most of them are monaural onset, often manifested as a weak hearing on one side of the ear, may also be accompanied by tinnitus, ear blockage, ear stuffiness, dizziness, nausea and other symptoms, need to comply with the medical advice of the audiological examination and further treatment. When the ear hearing is strong on one side and weak on the other, we should go to the ENT department of the hospital in time, through the examination to clarify the cause of the disease and standardize the treatment.