The ear is a complex and delicate organ that allows you to detect passing waves of sound energy and thus hear the sounds of the world around you. Sounds are actually invisible waves or vibrations that are collected by the outer ear. The unique shape of the outer ear functions like a radar dish, collecting the sound waves and funneling them down the ear canal to the ear drum.
The eardrum vibrates when the sound waves strike it. The normal human ear can distinguish between some 400,000 different sounds, some weak enough to cause the eardrum to move as little as one-tenth (1/10) the diameter of a hydrogen molecule.
Attached to the eardrum is a chain of three small bones called the ossicular chain. The ossicles are the smallest bones in the entire human body, and they are full size when we are born. The individual bones are smaller than a grain of rice, and they are named after objects which they resemble.
The bone attached to the eardrum is the malleus (hammer), the second bone is the incus (anvil) and the third is the stapes (stirrup). As the sound wave moves the eardrum, it moves the ossicles. The three bones actually form a lever system that transfers the energy of the sound waves from the outer ear, through the middle ear and into the inner ear.
The last bone in the ossicular chain, the stapes (stirrup), is attached to a tiny membrane called the oval window. The oval window is actually an entrance to the inner ear which contains the organ of hearing, or cochlea. When the stapes bone moves, the membrane in the oval window moves with it.
On the other side of the oval window is the fluid filled channel of the cochlea. This fluid is disturbed by movements of the membrane in the oval window. Inside the cochlea are thousands of microscopic hair cells which are set in motion whenever the fluid is disturbed. Stimulation of the hair cells, in turn, causes electrical impulses to be sent to the brain.
Most of the ear is hidden inside the head, so you are seldom aware of the job your ears are doing until they begin to fail. Fortunately, hearing aids can often help make up for lost hearing.
M.Ed., CCC/A,
received her 
M.Aud., CCC/A,
completed his
graduate degree at
the University of South Carolina. 
Attached to the eardrum is a chain of three small bones called the ossicular chain. The ossicles are the smallest bones in the entire human body, and they are full size when we are born. The individual bones are smaller than a grain of rice, and they are named after objects which they resemble.
The bone attached to the eardrum is the malleus (hammer), the second bone is the incus (anvil) and the third is the stapes (stirrup). As the sound wave moves the eardrum, it moves the ossicles. The three bones actually form a lever system that transfers the energy of the sound waves from the outer ear, through the middle ear and into the inner ear.
The last bone in the ossicular chain, the stapes (stirrup), is attached to a tiny membrane called the oval window. The oval window is actually an entrance to the inner ear which contains the organ of hearing, or cochlea. When the stapes bone moves, the membrane in the oval window moves with it.