Third window effect is seen in
Perforated tympanum
Dehiscent superior semicircular canal
Round window
Oval window
Ans. b. Dehiscent superior semicircular canal Dehiscence of bone overlying the superior semicircular canal can cause a constellation of vestibular and auditory symptoms and signs. These abnormalities can be understood in terms of the effect of the dehiscence in creating a third mobile window into the inner ear.