This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: ENT
[{'content': "Impedance audiometry is done in? \nSelect and explain. \nA. Otomycosis, B. Meniere's disease, C. Pressure changes in middle ear, D. Cholesteatoma", 'role': 'user'}, {'content': 'Answer: C \nExplanation: It is an objective test, widely used in clinical practice and is paicularly useful in children. It consists of: Tympanometry Acoustic reflex measurements By changing the pressure in a sealed external auditory canal and then measuring the reflected sound energy, it is possible to find the compliance or stiffness of the tympano-ossicular system and thus find the healthy or diseased status of the middle ear.', 'role': 'assistant'}]