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
Which of the following condition does show 'the third window effect' clinically? 
Select and explain. 
A. Perforated tympanum, B. Dehiscent superior semicircular canal, C. Round window anomaly, D. Oval window anomaly
B: Dehiscent superior semicircular canal
Answer: B: Dehiscent superior semicircular canal 
Explanation: The auditory and vestibular symptoms of dehiscent superior semicircular canal are due to exposure to external pressure along the dehiscent superior canal that is transmitted to the inner ear. The dehiscent poion of the superior canal acts as a third mobile window allowing acoustic energy to be dissipated there.