head injuries can result in deafness. Ear
infections can cause temporary deafness.
Too much earwax can also cause temporary
deafness. In some cases people lose
hearing because of listening to loud
noise. People often lose some hearing as
they get older, too.
Prevention and Treatment
Sometimes deafness cannot be prevented
or treated. This is the case when deafness
is caused by genes or by old age. However,
vaccines can prevent certain diseases
that might damage the ears. People
who work in noisy places can wear earplugs.
Hearing aids help people who are
partially deaf. They make sounds louder.
In some cases a doctor can perform surgery.
An example would be when an ear
passage is blocked. If nerves are damaged,
a doctor might put a cochlear
implant under the skin near the ear.
This device changes sounds into electrical
signals. The person then learns to
recognize those signals as sounds.
Deaf people can still communicate.
They can read lips. Some use their hands
to make signs for letters, words, and
ideas. This is known as sign language.
They can also learn to speak. Many are
helped by speech therapy.
Deaf people can use the telephone by
typing on a special keyboard. They can
also understand television shows
through the closed-captioning system.
This system translates the spoken words
The composer
Ludwig van
Beethoven
composed
some of his
greatest music
after he
became deaf.
A teacher uses sign language to
communicate with deaf students.
BRITANNICA STUDENT ENCYCLOPEDIA Deafness 21
to written words. The words appear at
the bottom of the screen.
#More to explore
Ear • Sign Language
Death
Death marks the end of life. When a
living thing dies, its body stops working.
All living things, including plants and
animals, go through the process of
death.
How Death Happens
In humans death can happen in many
different ways. Most people die from
diseases related to aging. Cancer, heart
disease, and other illnesses may cause
death. Some people die in accidents or
as a result of violence or natural disasters.
In some parts of the world people
die from warfare, starvation, or poor
nutrition.
A person dies when the body’s most
important organs—the heart, the lungs,
and the brain—stop working. Once
these organs fail, other organs also stop
working. Individual cells can survive
longer, but eventually they also die.
People used to be considered dead when
they stopped breathing and their heart
stopped. Today, however, special medical
techniques and equipment can restart
the heart and lungs. Many people now
consider brain death to be the end of
human life. Brain death happens when
the brain shows no signs of any activity,
even if machines are keeping the heart
and lungs working.
Dealing with Death
Every culture has its own customs for
dealing with death. Most of these customs
include either burial or cremation
(burning) of the body. In addition,
people often gather at funerals or other
services to honor the person who died.
Many people believe that, once the body
dies, a person’s mind or soul continues
in some kind of afterlife. Others think
that the body’s death is the end of that
person. People have always been interested
in what happens after death, but
no one knows for certain.
#More to explore
Living Thing
Death Valley
Death Valley is the lowest, hottest, and
driest point in North America. It got its
Cemeteries are final resting places for the
dead. Many members of the military and
other notable Americans are buried in
Arlington National Cemetery, near Washington,
D.C.
22 Death BRITANNICA STUDENT ENCYCLOPEDIA
name because of the hardships faced by
settlers attempting to cross the valley.
Death Valley is located in southeastern
California, in the United States. The
valley is about 140 miles (225 kilometers)
long and 4 to 16 miles (6 to 26
kilometers) wide. The lowest point in
the valley lies 282 feet (86 meters) below
sea level. Not far away towers Mount
Whitney, the highest point in the continental
United States. It is 14,494 feet
(4,418 meters) above sea level.
Summer daytime temperatures in the
valley often reach 120° F (50° C) in the
shade.Winter temperatures rarely fall to
freezing. The average annual rainfall is
only about 2 inches (50 millimeters).
Despite the extreme conditions, Death
Valley is home to a variety of plants and
animals. The plants include saltgrass,
cacti, and desert wildflowers. Animals
include lizards, rabbits, kangaroo rats,
coyotes, and bobcats. The largest animal
is the desert bighorn sheep.
For many years Death Valley was little
known except to the Panamint Indians
who lived in the area before the
Europeans came. Few people visited the
area until the 1870s. At that time, gold
was discovered in the surrounding
mountains. Death Valley’s extreme
environment now attracts tourists and
scientists. It was made a national park
in 1994.
#More to explore
California • United States
Declaration of
Independence
The Declaration of Independence is the
founding document of the United
States. On July 4, 1776, the
Continental Congress of the British
colonies in North America adopted the
declaration at Independence Hall in
Philadelphia. The document proclaimed
