The pharyngeal opening of the Eustachian tube is normally closed and only opens briefly during actions such as swallowing, yawning, wide mouth opening, and nose blowing to facilitate gas exchange in the tympanic cavity. If the muscles around the pharyngeal opening become paralyzed or atrophied, the opening may remain constantly open, leading to a condition known as abnormal patency of the Eustachian tube. Causes include defects in the surrounding soft tissues, scar adhesions, atrophy, and muscle paralysis, commonly seen in conditions such as atrophic rhinitis, pharyngitis, post-radiation nasopharyngeal mucosal atrophy, and myasthenia gravis. It can also be triggered by excessive mental stress, causing the muscles to remain in a state of tonic contraction. Symptoms include low-frequency tinnitus synchronized with breathing, worsened by speaking, mouth opening, or swallowing, and alleviated by lying flat, bending forward, or inhaling with the mouth closed. Patients may experience heightened self-hearing, difficulty understanding others' speech, and an unusually loud perception of their own voice.