A squeaky sound in the ear as soon as you open your mouth may be due to excessive cerumen, temporomandibular arthritis or dysfunction, otitis media and other diseases. 1. Excessive cerumen: If there is excessive cerumen in the external auditory canal, the squeaking sound in the ear occurs with the movement of the mouth when chewing or speaking, mainly due to the cerumen’s movement with the movement of the mouth, which then passes through the bone conduction and produces squeaking sound. 2. Temporomandibular arthritis or dysfunction: when temporomandibular arthritis or dysfunction occurs, it will lead to joint movement function being affected, and when the temporomandibular joint movement is not smooth when the mouth is opened, squeaking sound will appear in the ear, which will be accompanied by pain in temporomandibular joints, joints popping, and other discomforts. 3. Otitis media: When otitis media occurs, due to the presence of secretions in the ear, when the mouth is opened, the air pressure in the middle ear changes when the eustachian tube opens, causing the secretions in the ear to move, so you may hear squeaking sounds. Therefore, if there is a squeaking sound in the ear when you open your mouth, you should go to the hospital in time to improve the relevant examination and standardize the treatment after a clear diagnosis.