how Do We Hear | Why can we hear sounds | How does the ear work
Sounds from the outside world are picked up by the outer ear, which is made up of
the pinna and the ear canal. As the sound waves enter the ear, the ear canal (1)
serves to increase the loudness of those pitches that make it easier to understand
speech. At the same time, the ear canal protects another important part of the ear:
the eardrum (2) - a flexible, circular membrane which vibrates when touched by sound waves.
The sound vibrations continue their journey into the middle ear, which contains
three tiny bones called the ossicles(3-5), also known as the hammer, anvil
and stirrup. These bones form the bridge from the eardrum into the inner ear. They
increase and amplify the sound vibrations even more, before safely transmitting
them on to the inner ear via the oval window.
The inner ear, or cochlea (8), resembles the circular shell of a snail and houses
a system of tubes which are filled with a watery fluid. As the sound waves pass
through the oval window (6), the fluid begins to move, setting tiny hair cells in
motion. In turn, these hairs transform the vibrations into electrical impulses that
travel along the auditory nerve (9) to the brain itself. Exactly how the brain actually
translates these nerve impulses remains a mystery.
How Hearing Works
We don't just hear with our ears — we hear with our brains. How does it work? Find
out how simple vibrations become a birdcall, a rock lyric, or the blast of a jackhammer.
The Outer Ear
While the outer ear is a great place to display jewelry, it's specifically designed
to transmit sound. Sound begins as motion. When objects vibrate, molecules of air
are set in motion and transmitted as sound waves. The outer ear's bell-like contours
guide and focus these sound waves into the ear canal where they're aided and amplified
by its spiraling shape. This natural phenomenon works so well we copy it to hear
even better: a radio announcer cups his hand around his ear, simultaneously gathering
sound in and blocking background noise out. Once inside the ear canal, soundwaves
travel on until they reach the eardrum, the dividing point between the outer and
middle ear.
The Middle Ear
When sound waves hit the eardrum, they cause it to vibrate, sending the sound on
to the delicate machinery of the middle ear. Here, the body's three tiniest bones
— commonly referred to as the hammer, anvil and stirrup — mechanically advance and
organize the sound to further amplify it and facilitate its passage into the inner
ear. The middle ear also contains the eustachian tube, which equalizes air pressure
between the outer and inner ear.
The Inner Ear
The fluid-filled inner ear is where the action takes place. Here, microscopic hair
cells reside within the spiral-shaped cochlea. These hair cells are stimulated by
the soundwave moving through the fluid and convert that movement into nerve impulses
that are sent to the brain.
From Sound Waves To Brain Waves
Our brain interprets the signals and in turn tells us that the doorbell rang or
that words are being spoken. Many things help determine just exactly what it is
you hear but it's the combination of frequencies that give different sounds their
distinctive qualities. Source and direction of the sound and loudness are other
clues the brain uses to decipher messages. Hearing loss occurs when hair cells are
damaged or die, a common occurrence as we age. And hair cells, like brain cells,
do not regenerate. That's why most hearing loss is irreversible.
Your solution for hearing loss: Digital Hearing Instruments