Dullness of hearing in the ear belongs to ear blockage, which may be caused by cerumen embolism of the external auditory canal, cholesteatoma of the external auditory canal, acute suppurative otitis media and so on. 1. Cerumen embolism of the external auditory canal: When the cerumen secretion of the external auditory canal is excessive or its discharge is obstructed, it gradually forms a mass and blocks the external auditory canal, causing the symptom of muffled hearing in the ear. 2. Cholesteatoma of the external auditory canal: it is formed by the shed epithelial mass containing cholesterol crystals in the bone part of the external auditory canal. When the cholesteatoma is large, it can cause blockage in the ear, which will lead to the symptom of muffled hearing. 3. Acute suppurative otitis media: when the tympanic membrane is not perforated, a large amount of purulent secretion can remain in the tympanic membrane, causing increased pressure inside the tympanic membrane, resulting in tympanic membrane bulging, hearing loss and muffled sound in the ear. When there is muffled sound in the ear, it should be taken seriously and go to the hospital as soon as possible for a systematic examination to clarify the cause of the disease.