A.Equalize the pressure of air in the middle and external ear
B.Equalize the pressure of air in middle and internal ear
C.Facilitate the animal in hearing
D.Vibrate the tympanum
A.Equalize the pressure of air in the middle and external ear
B.Equalize the pressure of air in middle and internal ear
C.Facilitate the animal in hearing
D.Vibrate the tympanum