12. 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. impulses have to be sent to the brain through the auditory nerve. b. the brain has to interpret the direction from which the sounds are being delivered. c. vibrations have to be transmitted to the fibers of the auditory nerve. d. the outer ear has to collect the sound waves and lead them to the middle ear.