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
Impedance audiometry is done in? 
Select and explain. 
A. Otomycosis, B. Meniere's disease, C. Pressure changes in middle ear, D. Cholesteatoma
C: Pressure changes in middle ear
Answer: C: Pressure changes in middle ear 
Explanation: 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.