How the hearing system works

 
 
The outer ear: 
This includes the part of the ear on the outside of the head (“pinna”) and the ear canal. The outer ear serves to collect and funnel sound waves to the eardrum in the middle ear. 
 
The middle ear:
This begins at the eardrum. The eardrum is a thin membrane at the end of the ear canal. On the other side of the eardrum are three tiny bones called the ossicles. They are linked in a chain so that they connect the eardrum to the inner ear. The eardrum and the ossicles serve as a medium to conduct the sound waves to the inner ear. The Eustachian tube connects the middle ear to the throat and keeps the pressure in the middle ear equal to atmospheric pressure. 
 
The inner ear: 
This contains the balance system, the cochlea, and the auditory nerve. The cochlea is filled with fluid and lined with thousands of tiny nerve cells which convert sound vibrations into nerve signals which travel on the auditory nerve to the brain.  Sound is perceived in the inner ear and the sound message is understood in the brain. 
 
The sound waves are conducted inward via the outer and middle ear to the inner ear. The sound waves then vibrate the fluid in the cochlea, which in turn moves or “stimulates” the nerve cells in the cochlea. The nerve cells convert the vibrations into nerve signals and then pass the message to the auditory nerve and then up to the brain.