Which of the following has to happen before the eardrum begins to vibrate with the same frequency as the source of the sound waves? a. vibrations have to be transmitted to the fibers of the auditory nerve. b. the brain has to interpret the direction from which the sounds are being delivered. c. impulses have to be sent to the brain through the auditory nerve. d. the outer ear has to collect the sound waves and lead them to the middle ear.

D. The outer ear has to collect the sound waves and lead them to the middle ear.

Explanation:

Here when sound propagates through air then first the sound is collected by the outer part of the ear.

then it is propagated to the middle ear and then this will hit the ear drum situated at the inner ear.

Then this vibrations received on the inner part of year is converted into electrical signals and carried by the nerves to the brain.

then brain interpret these signals into sound

So here we will have

D. The outer ear has to collect the sound waves and lead them to the middle ear.