Education

Basic Ear Anatomy

Our remarkable sense of hearing is an intricate transfer of acoustic, mechanical  hydraulic and electrical energy that starts with what we know of as our ears and ends up inside our brain.

The human ear’s complex function can be divided up into three areas, the outer ear, the middle ear and the inner ear.

Outer Ear Anatomy

The most visible portion of the outer ear is called the pinna. Its unique shape of skin and cartilage is actually a sophisticated sound reception structure funneling sound waves into the ear canal.

The pinna’s affect can be accentuated by cupping the hand behind the outer portion. Sounds become louder and crisper as the hand gathers additional sound. The collected signals travel into the head through the ear canal. Along the way, the canal’s sound dynamics or resonance help reinforce the sound’s energy. 

Middle Ear Anatomy

The middle ear transfers the sound energy from the canal to the inner ear. To do this effectively, this area is filled with air through the Eustachian tube so that the air pressure is equal on both sides of the eardrum.

The middle ear transmits and amplifies the energy from arriving sound waves through movement of the eardrum and the three tiniest bones in the human body, called the ossicles. The ossicles are connected to the oval window, the entry point of the inner ear. 

Inner Ear Anatomy

Inside an intricate cavity within the skull, the inner ear contains three primary structures, the semicircular canals, the cochlea and the 8th or auditory nerve. The SCC consists of three loop-shaped, fluid-filled spaces that give us our sense of balance.

These canals extend into a snail shaped organ known as the cochlea. This is where the mechanical vibrations from the middle ear are converted into electrical impulses needed by the brain. The cochlea contains fluid and thousands of tiny nerve fibers, called hair cells. When the stapes moves the oval window, it displaces the cochlear fluid which moves the hair cells.

The most common type of hearing loss occurs when the hair cells’ movement is impaired or destroyed due to the aging process, disease, or excessive noise exposure. As the hair cells move, their nerve fibers are stimulated to produce corresponding electrical signals. These are collected into the auditory nerve which carries them to the brain. It is here that our sense of hearing actually occurs.

The brain perceives and interprets the impulses into what we know as sound and hearing. Damage, malfunction or interruption in any part of this delicate and elaborate mechanism likely results in our inability to hear correctly.