The eustachian tube is a ventilation channel located between the nasopharynx and the middle ear cavity. Eustachian tube dysfunction is a common cause of acute and chronic otitis media. There are several methods to examine the function of the eustachian tube: first, acoustic conductance testing to understand the function of the eustachian tube and middle ear cavity; second, electronic nasopharyngoscopy to understand the degree of opening of the pharyngeal opening of the eustachian tube and the presence of obstruction and compression lesions; third, eustachian tube imaging to understand the presence of eustachian tube blockage; fourth, CT and magnetic resonance imaging; fifth, eustachian tube blowing test, such as catheter blowing method, Bo’s ball blowing method or drinking and swallowing test, The fifth is the blowing test of the eustachian tube, such as the catheter blowing method, the Ball blowing method or the water swallowing test, etc.