Which of the following will not affect echolocation in bats?

The organ of Corti is situated on the .......

The stereocilia are projected from which part of the hair cell?

The Eustachian tube connects $A$ cavity with $B$. Choose the correct option for $A$ and $B$.

The $Oval$ $Window$ (fenestra ovalis) is an opening of the .....

Read the following statements regarding the structure of the human ear and select the correct option.
Statement $I$: The tympanic membrane is covered with mucous membrane on the inner side,to the surface of which is attached the $1^{\text{st}}$ ear ossicle,namely the incus.
Statement $II$: Scala vestibuli and scala tympani are filled with perilymph and form a part of the cochlea.