Hearing disorders

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HEARING DISORDERS

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Health Alert

Henry Wouk

HEARING DISORDERS


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Special thanks to Ren H. Gifford, PhD, director, Cochlear Implant Program in the Department of Otorhinolaryngology at the Mayo Clinic, for his expert reading of this manuscript.

Copyright 2011 Marshall Cavendish Corporation

Published by Marshall Cavendish BenchmarkAn imprint of Marshall Cavendish Corporation

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of the copyright owner. Request for permission should be addressed to the Publisher, Marshall Cavendish Corporation, 99 White Plains Road, Tarrytown, NY 10591. Tel: (914) 332-8888, fax: (914) 332-1888. Website: www.marshallcavendish.us

This publication represents the opinions and views of the author based on Henry Wouks personal experience, knowledge, and research. The information in this book serves as a general guide only. The author and publisher have used their best efforts in preparing this book and disclaim liability rising directly and indirectly from the use and application of this book.

Other Marshall Cavendish Offices:Marshall Cavendish International (Asia) Private Limited, 1 New Industrial Road, Singapore 536196 Marshall Cavendish International (Thailand) Co Ltd. 253 Asoke, 12th Flr, Sukhumvit 21 Road, Klongtoey Nua, Wattana, Bangkok 10110, Thailand Marshall Cavendish (Malaysia) Sdn Bhd, Times Subang, Lot 46, Subang Hi-Tech Industrial Park, Batu Tiga, 40000 Shah Alam, Selangor Darul Ehsan, Malaysia

Marshall Cavendish is a trademark of Times Publishing Limited

This book is not intended for use as a substitute for advice, consultation, or treatment by a licensed medical practitioner. The reader is advised that no action of a medical nature should be taken without consultation with a licensed medical practitioner, including action that may seem to be indicated by the contents of this work, since individual circumstances vary and medical standards, knowledge, and practices change with time. The publisher, author, and medical consultants disclaim all liability and cannot be held responsible for any problems that may arise from the use of this book.

All websites were available and accurate when this book was sent to press.

Library of Congress Cataloging-in-Publication Data

Wouk, Henry. Hearing disorders / by Henry Wouk. p. cm. (Health alert) Summary: Provides comprehensive information on the causes, treatment, andhistory of hearing disordersProvided by publisher. Includes index. ISBN 978-0-7614-4817-4 1. Hearing disordersJuvenile literature. I. Title. RF291.37.W68 2011 617.8dc22 2009028905

Front Cover: An X-ray view of a cross-section of the ear.Title page: A girl gets her ears examined by a nurse.

Editor: Joy BeanPublisher: Michelle BissonArt Director: Anahid Hamparian

Photo Research by Candlepants IncorporatedCover Photo: Oscar Burriel / Photo Researchers Inc.

The photographs in this book are used by permission and through the courtesy of:Aaron Bean: 13. Getty Images: Jose Luis Pelaez, 3; DEA Picture Library, 5, 11; Matthew Ward, 7; Dr. Fred Hossler , 15; Dr. Fred Hossler, 17; Brad Wilson, 26; 37, 39; Tara Moore, 49; AFP / Robyn Beck, 53. Alamy Images: Edward Moss, 9; Purestock, 20; Mary Evans Picture Library, 31; Corbis RF, 44, 47; The National Trust Photolibrary, 51; Trinity Mirror / Mirrorpix, 42. Photo Researchers Inc.: Chris Knapton, 21. AP Images: Barry Batchelor/PA Wire, 23; Tom Costello, 29. The Image Works: Mary Evans Picture Library, 33, 36.

Printed in Malaysia (T)6 5 4 3 2 1


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Contents

Chapter 1 What Is It Like to Have a Hearing 6

Disorder?

Chapter 2 What Are Hearing Disorders? 10

Chapter 3 The History of Hearing Disorders 28

Chapter 4 Living with a Hearing Disorder 46

Glossary 56

Find Out More 59

Index 61


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WHAT IS IT LIKE TO HAVE A HEARING DISORDER?

T hree-month-old Marie had a dangerously high fever. Her parents rushed her to the hospital. After a number of tests, doctors discovered that she had bacterial meningitis. The fluid surrounding her brain had become infected and was full of germs. After about a week and a half in the hospital, Marie seemed fine. She went home.

One day, a couple of weeks later, the wind slammed a door shut with a loud bang. Everyone jumped except Marie. She did not even blink.

The doctors told Maries parents that Marie did not hear the door slam because the infection had spread to her inner ear. The infection had damaged the cochlea, a delicate part of the bodys hearing system.


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First, the doctors gave Marie hearing aids. Hearing aids have tiny microphones and speakers that fit inside the ear and make sounds louder. The hearing aids seemed to help Marie. Her parents also enrolled her in a special school to learn American Sign Language (ASL). Now Marie could talk to her family by using hand gestures.

By the time she was three, Marie was frustrated. She could communicate with children who had hearing problems, but she could not talk to hearing children who did not know sign language. Marie could make sounds but not words.

Maries parents heard about an electronic device called a cochlear implant. They asked doctors if cochlear implants

This is the alphabet as spelled out by the American Sign Language.



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would be an option for Marie. The doctors said that cochlear implants were an option. The devices could help Marie hear better, and she could learn to speak. Marie would have to go through surgery to get the implants inserted.

During the surgery, doctors drilled tiny holes in each side of Maries skull. They used some wires to replace some damaged nerves in her ear. The wires were connected to receiver disks implanted under Maries scalp. Over each ear she wore sensors which picked up sound and sent it to the disks.

After her surgery, Marie visited an audiologist who turned on the cochlear implants. Marie wore special sound proces-sors on each ear. They looked a little like her old hearing aids. These sound processors were able to pick up sounds and deliver them to her cochlear implants.

Before long, Marie was taking special classes from a speech therapist. She learned how to speak more clearly and how to understand the sounds she was hearing. The solution worked well. One day Marie noticed for the first time that dogs have different barks. By the time she was five, Marie could speak clearly, and she did not have to rely only on sign language. She was able to play and talk with hearing children. Best of all, when her mother went away on business trips, she could call home and talk to Marie on the telephone.

By the time she was nine, Marie had an interest in music. Her singing was so good that she got a part in her school musical, The Wiz.

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This is a part of a cochlear implant. It relays sound signals into the inner ear.



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WHAT ARE HEARING DISORDERS?

O ur ability to detect sound relies on a system that is deli-cate, complex, and still a little mysterious. The human hearing system has many parts. If one part of the system wears out or breaks down, we can lose some or all of our ability to detect sound. Instead of using the word deafness, doctors prefer the term hearing loss because it is a more accurate way to describe what happens.

There are two different kinds of hearing loss: complete and partial. Complete hearing loss means a person cannot hear anything at all. Partial hearing loss means a person can detect some sound but cannot hear clearly with one or both ears. Think about the volume control on a radio or television set. If the radio is turned off and no sound is coming out of the speakers, that is like complete hearing loss. If it is turned

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down so low that you can hear only a little sound, that is like partial hearing loss.

HOW HEARING WORKS Hearing starts with sound. If sound were visible, it would look like waves of tiny particles called molecules flowing through

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The ear is not one simple organ but is made of three parts which transform sound waves into sound.

Outer ear

Inner ear

Middle ear


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the air. The ears gather up these waves and send them to the brain. The ear is made up of three sections: the outer ear, the middle ear, and the inner ear.

The Outer EarMuch of the hearing system is out of sight, deep inside the skull. What we usually think of as the ear is the soft, bendable tissue with an earlobe at the bottom. This tissue is called the pinna. The word pinna means wing in Latin. And, in fact, the outer ears do look like little wings sticking out of either side of the head.

Mammals are the only types of animals that have pinnae. Many mammals have special muscles attached to their ears. The muscles allow them to rotate their ears to hear sounds coming from different directions. Dogs and cats, for example, can move their ears without moving their heads.

People do not have these kinds of muscles, but their ears have other special features. Every persons pair of ears, or pinnae, has a unique shape. Ears are almost as individual as fingerprints.

The pinna is shaped roughly like a funnel. It gathers up sound waves and allows them to move into the ear canal. This is a tube in each side of the head. It is about an inch long and a quarter inch wide. The skin lining the canal has glands that make a substance called cerumen, better known as earwax. Cerumen serves many purposes. It coats the

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Some people may be able to wiggle their ears a little but no one can imitate animals, such as this cat, that can rotate its ears in many directions without moving its head.


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inside of the canal, traps dirt, and protects the ear canal from harmful bacteria. The canal constantly sheds earwax, which keeps the ear clean and clear.

The Middle EarSound waves travel beyond the end of the ear canal to the next section, which is called the middle ear. The middle ear begins with the eardrum, also called the tympanic membrane. The word tympanic comes from the Latin word for drum. The ear-drum is a membrane made of a thin piece of skin that covers the end of the ear canal. It is shaped like the top of a drum. Sound bounces against the eardrum and makes the surface vibrate.

On the other side of the eardrum is a tiny space called the middle ear. The middle ear is about the size and shape of an M&M candy. Inside the middle ear are three tiny bones called ossicles, a word that means little bones. The ossicles are the three smallest bones in the human body. They are hooked to one another like links in a chain.

Each ossicle gets its name from its unique shape. The first bone is the malleus, which is also called the hammer because it looks like a little hammer. The malleus is connected to the eardrum on one end. On the other end, it is linked to a second bone called the incusnicknamed the anvil because it looks like a tiny anvil. The incus connects the malleus to a third bone called the stapes. Sometimes the stapes is called the

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stirrup because it is U-shaped like the stirrup of a saddle. The stapes is the smallest bone in the human body. All the ossicles are inside a hollow area in each side of the skull called the tympanic cavity.


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The three smallest bones in the body are all in the ear. At the top is the malleus. The stapes is at the bottom left and the incus is at the bottom right.


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Moving downward from the middle ear to the back of the throat is an airway called the eustachian tube. It was named after an Italian doctor named Eustachius, who studied this part of the hearing system. Eustachian tubes provide room for air for the tympanic cavity and act as a drain for the middle ear. Sometimes infections cause fluids to build up in the middle ear. Eustachian tubes help keep the area clear by letting the fluid drain down into the back of the throat.

The eustachian tube also provides ventilation for the inner ear and helps the middle ear adjust to different amounts of air pressure. That is why passengers in an airplane may feel their ears pop. There is a difference in pressure between the air outside their heads and the air inside the middle ear space. The pop happens because the middle ear is adjusting to the pressure difference as the eustachian tubes allow air to enter the middle ear.

The Inner EarSound travels from the middle ear to the third section of the hearing system: the inner ear. The last bone in the middle ear, the stapes, is attached to a thin membrane called the oval window. This is part of a hollow, swirly bone structure called the cochlea. It is part of the inner ear. The name cochlea comes from the Latin word for snail because it has a shape like a snail shell.

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The cochlea has fluid inside it. When sound vibrations jiggle the three ossicles in the middle ear, the stapes pushes on the oval window and sends ripples through the liquid. The ripples tickle tiny hair cells located inside the cochlea. These cells look like stubby little hairs under a microscope. They move back and forth in the fluid. Different hairs respond to different pitches of sound. At the base, or bottom, of each cell is a clus-ter of nerves. When a hair moves, it stimulates those nerves.


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These are the inner ears hair cells as seen under a microscope. If they are damaged in humans they will not grow back.


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This triggers an electrical signal that travels to the acoustic nerve and then on to the brains auditory center, which sorts out the sounds. It is actually the brain that senses the differ-ences among music, speech, and birds singing. So, in a sense, we hear with our brainsnot just our ears.

OUR AMAZING SENSEHearing develops before birth. Doctors believe that infants can hear while they are still in their mothers wombs. Some experts think that babies in the womb may even be able to recognize their mothers voices. Pregnant mothers say they have felt their babies kick or twitch in response to loud noises.

Why do people have two ears? There are many advantages to having two instead of one. The first advantage is that it makes it easier to tell where a sound is coming from. Because ears are on opposite sides of the head, a sound will reach one ear at a different time than the other. The brain takes this information and can instantly figure out where a noise is coming from.

Another advantage of two ears is that they collect more information. This makes it easier to detect soft sounds and even to sift through sounds so we can hear what we need to hear. That is why you can hear your name called out in the middle of a noisy room. Experiment with this advantage by plugging one of your ears with your finger in a very noisy

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place. Then you can tell how much harder it is to follow a conversation with just one hearing ear.

The hearing system keeps the body balanced. In each side of the skull, the inner ear has structures called semicircular canals. These three bony hoops contain fluid and microscopic hair cells. One loops straight out to the side. One goes upward. The third loops downward.

When the head tilts, the fluid inside the ears moves. That tickles the hair cells, which tell our brain if our head or body is tilted. The brain uses that informationas well as sights and other sensationsto keep the body balanced. This is called the vestibular system. Everyone from a tightrope walker to a person taking a stroll needs this system. Without it, we would find it extremely difficultif not impossibleto run or even to walk without falling over.

HARD OF HEARINGAbout 36 million Americans have some sort of hearing loss. Experts say that the number of people with hearing problems is growing. It may get as high as 78 million by 2030. Hearing loss can fall into one of three general categories: conductive, sensorineural, and mixed.

The term conductive hearing loss describes anything that keeps sound from getting to the inner ear. Ear infections are one of the most common causes of conductive problems in

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infants and children. Children have short eustachian tubes that are not as vertical as an adults. When a child gets a cold and germs move to the middle ear, the body reacts by building up fluid. This fluid cannot drain easily through the childs eusta-chian tubes due to the tubes small size and orientation. The extra fluid muffles the vibration of the small bones in the ear, and makes it difficult to hear.

When the inner ear is fighting an infection, what can result is a build-up of fluid, shown in this computer illustration in blue.


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Another common cause of conductive hearing loss is getting something stuck in the ear canal. Children sometimes poke things in the ear canal. Other times, adults and children may have too much earwax. Sometimes earwax builds up, forms a plug, and blocks out sound.

Fortunately, conductive hearing loss usually can be solved easily. Doctors can prescribe medicines or ear-drops to clear up infections. Where there is a buildup of earwax, they can remove the wax with warm fluids or with a small, hoop-shaped tool.

Sensorineural hearing loss is more complex because it involves inner ear damage. People can suffer from sensorineural hearing loss if they have been exposed to loud noises or have had head injuries. Some people are even born with sensorineural hearing loss. This is generally the result of a genetic tendency for hearing loss. Diseases such


People should never stick anything in their earseven a cotton swab. A doctor can remove built up earwax witha swab or other tools.


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Buzz Off

One day the daughter of British inventor Howard Stapleton came home very upset. Some teenage bullies hanging out near a local store had been harassing her. Stapleton knew that the store owner had been complaining about gangs bothering his customers. He had an idea.

When Stapleton was a boy visiting a factory with his father, he complained about the high-pitched sound that some of the machinery made. His father didnt know what he was talking about. Years later, Stapleton learned why. Adults could not hear the high-pitched factory noise because they had less sensitive hearing. All people start to lose their ability to hear high-pitched sounds starting around age twenty. Most people do not recognize this loss since it happens gradually.

Stapleton designed an electronic noisemaker. He called it the Mosquito because it generated a high-pitched sound that only younger peopleincluding teenage bulliescould hear. The store owner put the Mosquito outside his shop and turned it on. Within minutes, the teenagers left. The shrill noise bothered the teenagers, but the stores adult customers did not even notice it. Soon other businesses began ordering the Mosquito.

The Mosquito has been used for other purposes. Some imaginative teenagers have downloaded the sound into their cell phones. They use it as a special ring tone for text messages. They like it because they can hear the ring, but their teachers cannot. They can check text messages in class without getting caught.


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The Mosquito device seen in the wire cage is used by some business people in England to keep teenagers from gathering outside their stores.

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as measles, mumps, and meningitis can interfere with hearing if the infection spreads to the inner ear. High doses of some drugs, such as antibiotics, can cause hearing loss by damaging delicate hair cells.

A persons sex and age also make a difference. Men tend to experience sensorineural hearing loss more often than women. As people get older, their hearing starts to fade. Older people are not as able to hear high-pitched sounds as they were when they were younger. This condition of losing hearing as we age is called presbycusis.

The third kind of hearing loss is called mixed hearing loss. This type of loss involves both conductive and sensorineural components. One example of a mixed hearing loss would be someone who is born with a genetic type of sensorineural hearing loss but also has a conductive hearing loss from an ear infection.

PHANTOM NOISEAnother condition related to hearing is called tinnitus, which comes from the Latin word for ringing. A person who has tinnitus hears sounds like buzzing, ringing, whistling, or hiss-ing in one or both ears. Only the person with tinnitus can hear these noises. For that reason, tinnitus is sometimes called a phantom noise.

Tinnitus can be present all the time, or it can come and go.


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For example, a person might experience tinnitus for a few seconds if he or she stands too close to a loudspeaker at a concert or if a firecracker goes off nearby.

Usually tinnitus is a problem for older adults. Most people have experienced tinnitus at least once in their life. This is considered normal. Doctors do not fully understand what causes tinnitus, but they think it is caused by inner ear damage.

TESTSThere is no one test that can detect all hearing problems. One of the most commonly performed tests, however, is called an otoscopy. Otoscopy is the act of examining the ear canal, ear-drum, and part of the inner ear. Doctors use an otoscope to perform an otoscopy. An otoscope is a small, L-shaped flashlight. It has a magnifying lens that allows doctors to look deeply into the ear canal. With an otoscope, doctors first check to see if the ear canal is blocked with wax or other foreign objects. Then they check the color of the eardrum to see if it is infected. Finally, they look at the eardrum and check for any tiny holes.

Doctors also test hearing with tuning forks. First, doctors gently tap the tuning fork to make it vibrate and hum. Then they hold the tuning fork close to the patients ear so the patient can hear it hum. Next, doctors tap the fork again and touch it to the skull behind the ear.

A person with normal hearing will hear the hum longer when


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By looking into a patients ear with a magnifier flashlight called an otoscope, doctors can learn a lot about how healthy the ear is.


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the fork is near his or her ear than when it touches the skull. But if the patient has conductive hearing problems, he or she will hear the sound more clearly when the tuning fork touches the head than when it is next to the ear.

In another test, doctors tap the tuning fork and touch it to the middle of a patients forehead. Normally, both ears should detect the sound at about the same volume. If this does not happen, there might be a problem with the inner ear, or there might be fluid behind one of the eardrums.

To test how well a person can hear different pitches, the patient has an audilogic (hearing) evaluation. The patient sits in a soundproof room, puts on a set of headphones, and listens to different tones played at different volumes in each ear. This test allows doctors to determine the seriousness of a hearing problem. It also reveals which ear has the problem.

When children are too young to turn their heads in response to sound, doctors check their hearing systems by using an auditory brain stem response test. A machine sends clicks or tones to each ear through headphones or earphones. Doctors place electrodes on the childs scalp and ear lobes to record brain waves in response to the sounds. Doctors compare these to the brain waves of people with normal hearing. If the childs pattern is different, he or she might have hearing loss.


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THE HISTORY OF HEARING DISORDERS

F or years, people with serious hearing loss had to live an isolated life, cut off from the rest of the world. Now that is no longer true. Just as we have different ways of discovering hearing problems, we now have amazing ways of fixing them.

In 1995, the Miss America Pageant crowned its winner: Heather Whitestone of Alabama. Whitestone had trouble hearing the announcement, but it was not because she was nervous. It was because she had been almost totally deaf since she was an infant. For the first time in its seventy-five-year history, the famous pageant had crowned a winner with a disability.

Had Heather Whitestone lived in another century, her life would have been much different. Instead of being applauded and receiving a crown, she would have been an outcast.

For centuries, deaf people suffered terrible discrimination.

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Heather Whitestone became the first deaf winner of the Miss America pagent in 1994. Here she signs I love you to the crowd after she wins the crown.

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More than two thousand years ago, the Greek philosophers Aristotle and Plato said that if people could not hear, they could not be taught. In ancient Rome, deaf people did not have the full rights of citizens. They could not own property. One religious writer, St. Augustine, declared that parents who had a deaf child were being punished by God.

THE SIXTEENTH AND SEVENTEENTH CENTURIESIt took centuries before these ideas changed. In the 1500s, an Italian doctor and mathematical genius named Girolamo Cardano became interested in deafness because his oldest son had no hearing in one ear. Cardano experimented with a series of images that he thought could be used to teach the deaf. He called the images visual codes. Cardano was the first person to say that Plato and Aristotle were wrong. Being unable to hear, he said, does not prevent a person from learning.

About a century later, a British doctor named John Bulwer agreed with Cardano. Bulwer thought people could communi-cate with their hands. Since people already used gestures to communicate some of the time, he thought it would be natural for deaf people to use a system of hand movements to express their thoughts. He suggested an alphabet sign language. Different hand and finger movements would represent letters. With these hand movements, a deaf person could spell out words.

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Girolamo Cardano was an Italian doctor who believed in the rights of deaf people.


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Around the same time in Spain, a monk named Pedro Ponce de Leon had a similar idea. His fellow monks had taken a vow of silence, so they did not speak. Even so, sometimes they had to tell each other something. He noticed that they used a sys-tem of hand signals to communicate. De Leon thought it might be possible to use similar signals to teach the deaf. He got his chance to try out the idea when a wealthy Spanish family asked him to teach their two deaf sons.

The laws in Spain said that a person had to be able to read and write in order to inherit family property. Without these skills, the two children would get nothing. De Leon used alphabet signs that had been developed by another Spanish monk, Melchor de Yebra. De Leon successfully taught the two boys how to read and write. He also worked with deaf children from other wealthy families.

THE NINETEENTH CENTURYFor years, only the children of the rich got this kind of educa-tion. That changed in the 1800s. One day a French priest, Abbe Charles-Michel de LEpee, met two girls from a poor family. At first he thought they were rude because they did not answer when he spoke to them. Then he found out they had been deaf since birth.

De LEpee discovered that deaf people in Paris had devel-oped their own sign language. He learned those signs and


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began teaching the two girls how to communicate using them. The girls were bright, and they learned quickly. De LEpee thought other deaf children should be taught as well. Gradually he developed his own system of hand signals. He produced a dictionary of his sign language.

De LEpee showed how accurate his language was by using special theater demonstrations. He would give a speech, and

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In the nineteenth century, the French priest Abbe Charles-Michel de LEpee, shown stand-ing, developed methods to teach deaf children which are still used today.


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Island of the Deaf

Six miles off the coast of Massachusetts is a small island called Marthas Vineyard. In the 1600s, a group of English settlers moved there. Over the years their families married one another. Many of the settlers carried an inherited tendency for deafness. As a result, about one of every four children was born deaf. But the people adjusted. Over time, the island residents developed their own sign languagethe first ever used in the United States.

Many of the deaf families settled in a Marthas Vineyard town called Chilmark. Deafness was so common there that town meetings were conducted in sign language. Hearing people who moved there were outnumbered. They had to learn sign language to communicate with their neighbors.

Eventually the deaf children married people outside their communities. The number of deaf people on the island dropped. By the 1950s, the last deaf person born on Marthas Vineyard died.


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at the same time he would say it in sign language. One of de LEpees students would sit on the other side of the stage and write down what de LEpee signed. The audience was always amazed when the student reproduced an exact copy of de LEpees dictation in perfect French.

De LEpee believed that all hearing impaired children, not just those with rich parents, should be educated. He was from a wealthy family himself, and he used all his money to open the worlds first free school for deaf children in Paris.

Similar events were happening in other parts of Europe. In England, a wealthy man asked a teacher named Thomas Braidwood to teach his deaf son mathematics. Braidwood found he had a talent for teaching. In 1783, he started the first school for the deaf in England.

In Germany a teacher named Samuel Heinicke thought it might even be possible to teach deaf children to speak. His method was to put the hand of a deaf person on his throat and have the student feel the vibrations that his voice box made when he said different words. In this way, some of Heinickes students learned to speak.

In the 1800s, the idea of special schools for the deaf spread to the United States. It began in Hartford, Connecticut, with a nine-year-old girl named Alice Cogswell. She was born a healthy baby. As a little girl, however, she caught scarlet fever, and the infection destroyed her hearing. Her father, a wealthy

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doctor, tried different ways to help her learn, but noth-ing seemed to work well. After his neighbors son Thomas Hopkins Gallaudet stopped by, Dr. Cogswell had an idea.

Gallaudet was impressed by how smart Alice was. During one of his visits he taught Alice to write the word hat. He taught her a few more words on later visits. Dr. Cogswell had read about Abbe de LEpees school in Paris. He knew there were several hundred deaf children on the East Coast, and he thought they could benefit from a similar school in the United States.

Dr. Cogswell convinced Gallaudet to travel to Europe and learn about the French system. Gallaudet did better than that. He brought back one of the teachers, a French man named

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Thomas Gallaudet was an American educator who helped set up teacher training institutions for deaf people.


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Laurent Clerc, who had been a deaf student at de LEppes school. In 1815, Clerc traveled to Hartford and helped Gallaudet set up the American School for the Deaf in Hartford. It was the first of its kind in the United States. The schools first student was Alice Cogswell.

The school was so successful that others like it began appearing all over the countryin New York, Pennsylvania, and Kentucky. In the 1860s, the worlds first college for the deaf was established in Washington DC. It was called the National


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Gallaudet University is the only university exclusively for deaf students.


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Silent Signals in Sports

Shortly before the beginning of the twentieth century, a man named William Dummy Hoy made headlines in sports. He was the first deaf man to play Major League Baseball. Hoy changed the way the game was played. The story goes that when Hoy was up at bat, he could not hear the umpire call out strikes and balls. So he devised a system of hand signs and asked his teams third base coach to tell him which pitches were balls and which were strikes. Eventually home plate umpires adopted the same signals. Today, umpires use all kinds of hand signals when they make their calls.

Deaf players also changed the game of football. In the 1890s, Gallaudet University had a football team. Its quarterback, Paul Hubbard, used sign language to tell his team what the next play would be. He was worried that players on the other team would read his signs, so he gathered his team around him in a circle. Other football teams copied the idea, and the football huddle was born.


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This major-league umpire signals a strike during a baseball game. This is just one of the signals umpires use to communicate during a game.


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Deaf Mute College. Its president was Edward M. Gallaudet, the youngest son of Thomas Gallaudet. Later it changed its name to Gallaudet University, in honor of Alices teacher, Thomas Gallaudet.

The 1800s was an era of disagreement about the best ways to teach the deaf. There were two approaches. Some thought it was better to use sign language. Others thought it was better for hearing impaired people to learn to communicate by reading lips and speaking. This second technique was called vocalizing.

Alexander Graham Bell, the inventor of the telephone, was one of the people who believed vocalizing was better than sign language. Deafness had been a part of his life since he was a child. His mother was deaf, and as a boy Bell had talked to her in sign language. Bell also worked as a teacher of the deaf at a school in Boston. His wife had been one of his students.

Bell and others believed that relying only on sign language restricted a person to communicating only with other deaf people. By learning to vocalize, a deaf person could talk to everyone.

In 1880, educators who worked with the deaf met at a world convention. They decided to stop teaching sign language and teach only vocalizing. Deaf students were forbidden to use sign language. In some schools, teachers tied the hands of students caught signing.

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Not everyone agreed with this. Teachers in the United States con-tinued to teach sign language. The controversy went on for years. Eventually schools became less rigid about their methods. Today most schools now teach a combi-nation of techniques: lip reading, vocalizing, and sign language.

THE TWENTIETH CENTURYFor centuries, schools helped deaf people learn and communicate but could do nothing to improve their physical disabilities. It was not until the twentieth century that this began to change.

Over the years, there were all kinds of folk remedies to cure deafness. Most were strange or silly. For example, one cure was to stick a twig in the peoples ears and leave it there for a day and a night. Another was to put pepper in the peoples mouths


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Royal Hearing Device

The king of Portugal, Goa IV, was hard of hearing. In 1819, furniture makers built him a special throne with openings in each arm of the chair. When people needed to speak to the king, they talked into the openings. Speaking tubes inside the arms magnified peoples voices. The king listened through a rubber hose con-nected to the hollow arms.


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while they yawned to make them sneeze. The sneeze was sup-posed to take away the deafness.

One of the oldest methods is something called candling. A person lies on his or her side while a healer places a small

candle in one ear and lights it. The flame is somehow sup-posed to draw out impurities from the ear and take care of ailments, from earaches to hearing problems.

After the twentieth century began, inventors created more useful tools for deaf people. One strategy was to make sounds louder. The first hear-ing aid was something called an ear trumpet. It was basical-ly a tube shaped like a horn. The small end was placed in his ear, and the large end was aimed at the sound.

Later researchers discov-ered that they could make

sound louder by adapting parts of the telephone invented by Alexander Graham Bell. In these early models of a hearing aid,

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In the early 1900s hearing aid devices were very large and cumbersome. This woman shows how an ear trumpet from 1911 was used.


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a person used a microphone copied from the mouthpiece of the telephone. The microphone was connected to a headphone like the telephones earpiece.

The first electric hearing aids were clumsy. The batteries powering them were very big, and the microphone was in a large box that the user would set on the table. As batteries got smaller, so did the hearing aids.

By the 1950s, scientists managed to miniaturize the wiring of a hearing aid into tiny electronics packages. Hearing aids were so small that they could be hidden in eyeglasses or worn hooked over the ear. Todays hearing aids are tiny enough to fit completely inside the ear. Whatever the size, all these hear-ing aids worked the same way: they made faint sounds louder.

Another invention made a big difference in the lives of deaf people. It was a machine called the telephone typewriter (TTY). In 1964, a deaf scientist named Robert Weitbrecht decided to take a machine called a radio teletypewriter and change it to help the deaf.

Using a radio teletypewriter, a sender would type a message on a keyboard. That message would travel over radio waves to a receiving unit, which printed out the message. Weitbrecht changed this machine so it could send and receive typed messages over telephone lines. Using the TTY, two deaf people could call each other. They typed their conversation the way people do now with texting. Today there are special

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There are many devices to help the hearing impaired. This is a telephone at an airport for those who are hard of hearing.


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TTY translation services that allow a deaf person to call a hearing person. A specially trained operator reads the TTY message to the hearing person and types the answer to the deaf caller.

In the 1970s, television networks started broadcasting shows with closed captions. These are typed versions of the words that are being spoken. A whole world of entertainment opened up to hearing impaired people. Then, in the 1980s, doctors made the first step toward developing a bionic ear with the cochlear implant. This is an electronic device that feeds sound to the brain through the cochlea and the acoustic nerve.

Cochlear implants are for people who have lost most or all of their hearing and can hear very little with hearing aids. It gives the ability to hear to people who could hear little or nothing before. One deaf person who has cochlear implants is former Miss America Heather Whitestone.


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LIVING WITH A HEARING DISORDER

L ife has gotten better for people with hearing loss. It has also gotten more complicated because of the many choices they have. For example, hearing aids are now smarter. For years, they were basically tiny microphones that picked up sound and made it louder. That was fine in a quiet room, but it did not help if a person was in a noisy restaurant. Everything, including background noise, became louder. Many people stopped using hearing aids for this reason.

Today there are newer, digital hearing aids. Built into them are tiny computers that turn sound into bits of data. The computer can keep loud background noise softer and bring out the softer sounds of the nearest voice.

Digital hearing aids are more complicated than older models. Each one has to be programmed for a specific users


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hearing needs. But they are smaller and sturdier, and they use less battery power. And if a persons hearing gets worse, he doesnt have to get a new hearing aid. He can just have his digital model adjusted.


As electronic circuits got smaller, so did the size of hearing aids which fit behind or even inside the ear canal.

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How Loud Is Too Loud?

More than one out of every ten Americans has a condition called noise-induced hearing loss. This is caused by loud noise.

Hearing experts measure the loudness of sound with units called decibels (dB for short). The louder the sound, the higher the number of decibels.

Sounds of 75 decibels or less are safe, but exposure to noise above 85 decibels can be damaging. Time is also a factor. Exposure to sounds that are 100 decibels or louder for more than 15 minutesor to sounds louder than 110 decibels for more than one minutecan seriously damage a persons hearing. Here are some typical decibel measurements and the level of danger:

SAFE Silence 0 dBA whisper 15 to 30 dBNormal conversation 60 dB

RISKY (more than 85 dB)Lawn mower 90 dBMotorcycle or snowmobile 100 dBPersonal music player at max volume 105 dBChain saw or rock concert 110 dB

DANGEROUSAmbulance siren 120 dBA gunshot or firecracker 140 dB


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Hearing experts warn that people who play their music so loudly that they cannot hear any other sounds around them are putting their hearing at serious risk.


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ELECTRONIC HELPERSSeveral other new gadgets also help make life easier. People with hearing problems can use special electric alarm clocks connected to wake-up vibrators. The user sets the alarm and puts a vibrating disk under the pillow. When the alarm goes off in the morning, the shaking disk wakes the person. There are special digital watches that use the same system. The user sets the alarm, and the watch vibrates at the chosen time.

Many deaf households have a system of warning lights. If someone rings the doorbell, a specific light goes on. When the phone rings, a light marked Telephone flashes. Special smoke detectors have superbright strobe lights that go off when they detect a fire.

ANIMAL HELPERSJust as blind people have seeing eye dogs, some deaf people have special hearing dogs. The dogs are trained to recognize specific sounds and signals such as a baby crying, fire alarms, smoke alarms, oven timers, ringing telephones, doorbells, and knocks at the door. When they hear one of these sounds, the dogs go to the owners, paw them to get their attention, and lead them to the source of the sound.

PROTECT YOUR EARSOne of the scary facts about hearing is that once it is dam-aged, it does not recover. That is why hearing experts urge

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Dogs can now be trained to act as a persons ears by learning to recognize the important sounds in a persons life from doorbells and telephones to smoke alarms.


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us to take special care of our ears. Doing that is not compli-cated or difficult. Here are some recommendations:

Limit the time you are exposed to loud noise. People can become used to high levels of loudness. When you use headphones, do not listen to music at a louder volume than is healthy.

Wear ear protection, such as earplugs or soundproof headphones, when you are near loud sounds such as live rock music, leaf blowers, lawn mowers, and power tools.

Set the volume on your stereo or MP3 player no higher than 50 percent of the loudest setting.

Never turn up the volume on personal music players high enough to block out noisy surroundings. If you cannot hear people speaking, the music is probably too loud.

Keep track of how much time you spend listening to music.

Take quiet breaks from a noisy situation.

HOPE FOR THE FUTUREComputer technology is making a huge difference in the world of hearing loss. One recent technological breakthrough is called automatic speech recognition (ASR). This is a program that can listen to a persons spoken words and turn them into print.

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There is a special telephone that uses ASR. When a speaking person calls someone with a hearing disability, the call is sent to an electronic translation service. The translator displays the spoken words on a small screen.

Today deaf students at the Rochester Institute of Technology in Rochester, New York, can attend regular college classes


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A gadget called VPAD+ is a videophone developed for deaf and hard-of-hearing people. Through the video screen, callers can communicate via sign language. If the caller does not know sign language, a third party sign interpreters services are offered.


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because of ASR. As the teacher talks, a person watching the class repeats the professors words into a computer, which dis-plays the words on a screen. This process is faster and simpler than having an interpreter or a stenographer.

Right now ASR programs are limited. They can translate most but not all spoken words. The programs can only be trained to understand one speaker at a time. In addition, there is a short time lag between when a word is spoken and when it is displayed. The reason for the delay is that the computer has to find the word in its memory sound bank and then print it out.

Scientists think that people with hearing loss might some-day carry a small listening machine with a microphone hooked to an ASR computer. They could aim the microphone at some-one talking and see what the person is saying on a screen.

Other improvements are being made for people with hear-ing loss. Doctors at Ohio State University Medical Center have two electronic devices that they say work better than hearing aids. One is called a middle ear implant. To use a middle ear implant, doctors attach a tiny magnet to the stirrup bone of the middle ear. On the outside of the persons head they place a small receiver and transmitter that takes sound and sends it as a magnetic pulse into the head and to the magnet. This makes the bones vibrate and send sound to the cochlea. It produces a clearer sound than any hearing aid.

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The other device uses bone as a sound magnifier. It is called BAHA, short for bone-anchored hearing aid. Bone is an excellent conductor of sound. With the BAHA system, a surgeon screws a small metal post into the skull behind the ear. He or she attaches to it a sound processor about the size of a half-dollar coin. This sound processor turns sound into vibrations. The metal post picks up the vibrations and sends them to the cochlea. Unlike a cochlear implant, this does not destroy the delicate hair cells in the inner ear, and it requires a simpler surgery.

Someday, doctors hope, a true cure for deafness will come when scientists learn how to grow new hair cells in the ear. One of the great mysteries of science is why the hair cells of some animals, such as birds, grow back while this does not happen in humans. Right now researchers at the University of Oregon are trying to grow replacement hair cells in deaf mice. One scientist at Stanford University in California thinks there could even come a time when doctors will treat damaged hair cells with special ear drops. This is good news for all of us who live in a world that gets noisier by the day.


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Glossary

acoustic nerveThe connection between the inner ear and the brain.

American Sign Language (ASL)A language of hand signals and facial expressions used by deaf people in the United States and Canada.

antibioticsMedications that either kill germs or stop them from spreading.

audiologistA person who studies hearing disorders.auditory brain stem response testA test that measures the

brains response to sounds. auditory centerThe part of the brain that receives sound

from the ears and analyzes them.automatic speech recognition (ASR)The digital transforma-

tion of spoken words into text.bacterial meningitisAn infection of tissue in the brain. cerumenEarwax.cochleaA spiral cavity inside the head where sound vibrations

are turned into nerve impulses.cochlear implantAn electronic hearing device implanted in

the head to send sound directly to the cochlea. conductive hearing lossDifficulty hearing caused by problems

in the outer or inner ear.

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GLOSSARY

decibelsUnits that measure the loudness of a sound.ear canalA tube running from the outer ear to the middle

ear.eardrumThe thin membrane of skin at the inner end of the

ear canal.eustachian tubeA narrow tube that goes from the back of

the throat up to the middle ear.hair cellsMicroscopic cells that convert sound into electrical

signals inside the cochlea.incus (anvil)One of three tiny bones of the inner ear. It

is shaped like an anvil and sits between the other two ossicles.

inner earThe most complex section of the ear. It is connect-ed to the brain by the auditory nerve.

malleus (hammer)One of the three tiny bones of the ear. It is shaped like a hammer and is connected to the eardrum.

middle earThe portion of the ear that includes the eardrum and the cavity inside the head.

middle ear implantA hearing aid in which a listening unit outside the head sends magnetic signals to a receiving unit attached to the bones of the inner ear.

ossiclesThree tiny bones of the middle ear that relay sound vibrations to the inner ear.

outer earThe part of the ear that is outside the head, as well as the ear canal.

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otoscopyA doctors examination of the ear canal and eardrum with a special light.

oval windowA tiny membrane of skin in the cochlea that helps send sound from the middle ear to the inner ear.

pinnaThe flap of skin and cartilage that sticks out on either side of the head. This is what most people call an ear.

presbycusisA type of hearing loss that occurs as people get older.

semicircular canalsThree half circles of hollow loops inside the head that help maintain balance.

sensorineural hearing lossHearing problems that result from damage to nerve tissue.

speech therapistAn expert who treats speech problems.stapes (stirrup)The smallest of the three bones of the

middle ear. telephone typewriter (TTY)A special device that allows a

deaf or hard-of-hearing person to send and receive typed messages over a phone line.

tinnitusA ringing or buzzing sound in the ears that is not caused by an outside source.

tympanic cavityA small space, located inside either side of the head, that surrounds the bones of the middle ear.

tympanic membraneAnother name for the eardrum.vestibular systemA system that keeps the body balanced.

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FIND OUT MORE

BooksLandau, Elaine. The Sense of Hearing. New York: Childrens Press, 2009.

Van Cleve, John Vickrey. The Deaf History Reader. Washington DC: Gallaudet University Press, 2007.

Yost, William A. Fundamentals of Hearing. Burlington, MA: Elsevier, 2007.

WebsitesAmerican Speech-Language-Hearing Associationwww.asha.org/public/hearing/disorders/types.htm

Centers for Disease Control and Prevention: Hearing Losswww.cdc.gov/ncbddd/dd/ddhi.htm

Hearing Loss Association of Americawww.hearingloss.org/

Mayo Clinic: Hearing Losswww.mayoclinic.com/health/hearing-loss/DS00172

FIND OUT MORE

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National Institute on Deafness and Other Communication Disorders www.nidcd.nih.gov/index.asp

New York Online Access to Health: The Ear and Hearing/Balance Disorderswww.noah-health.org/en/ear/

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INDEX

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Index

Page numbers for illustrations are in boldface.

acoustic nerves, 18, 45age, hearing loss and, 2223, 24, 25animals, 12, 13, 50, 51, 55audilogic (hearing) evaluations, 27auditory brain stem response test, 27automatic speech recognition (ASR), 5254

babies, 18, 20bacterial meningitis, 6balance, 19Bell, Alexander Graham, 40, 42bone-anchored hearing aid (BAHA), 55Braidwood, Thomas, 35brains, 6, 18, 19, 27, 45Bulwer, John, 30

candling, 42Cardano, Girolamo, 30, 31cats, 12, 13cerumen. See earwaxchildren, 20, 22 see also teaching deaf childrenClerc, Laurent, 37closed captions, 45cochlea, 6, 1617, 5455cochlear implants, 78, 9, 45, 55Cogswell, Alice, 3536, 37complete hearing loss, 1011conductive hearing loss, 1921, 24, 27

deafness. See hearing lossde Leon, Pedro Ponce, 32de LEpee, Charles-Michel, 3233, 33, 35, 36

discrimination against deaf people, 28, 30dogs, 12, 50, 51

ear canals, 12, 14, 21, 25eardrums, 14, 25, 27ears, 11, 1218, 13, 21 protecting, 4849, 49, 50, 52ear trumpets, 42, 42earwax, 12, 14, 21, 21, 25Eustachian tubes, 16, 20

fluid, 6, 19, 20, 20

Gallaudet, Thomas Hopkins, 36, 3637, 40Gallaudet University, 37, 38, 40Goa IV (king, Portugal), 41

hair cells, 17, 17, 19, 24, 55hearing, description of, 1119hearing aids, 7, 42, 4243, 4647, 47, 5455hearing loss description of, 1011, 1921, 2425, 27 hereditary, 21, 24, 34 history of, 2845 living with, 4647, 5255 treatments for, 21, 4142, 5455Heinicke, Samuel, 35Hoy, William Dummy, 38Hubbard, Paul, 38

incus bones, 14, 15infections, 6, 1920, 20, 24, 25, 42inner ears, 11, 1618, 17, 1920, 20, 21, 24, 25, 27

lip reading, 40, 41


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malleus bones, 14, 15Marthas Vineyard, hearing loss on, 34middle ears, 11, 1416, 20, 5455mixed hearing loss, 24Mosquito device, 22, 23

nerves, auditory, 1718noise-induced hearing loss, 4849, 49

ossicles, 1415, 15, 1617, 20otoscopy, 25, 26outer ears, 11, 12, 14oval window membranes, 16

partial hearing loss, 1011pinna, 12presbycusis. See age, hearing loss and

semicircular canals, 19sensorineural hearing loss, 21, 24sign language, 7, 7, 8, 30, 3235, 3839, 39, 40, 53sound, 10, 1112, 14, 1618speaking tubes, 41speech, learning, 8, 35sports, sign language in, 3839, 39stapes bones, 1415, 15, 1617Stapleton, Howard, 22

teaching deaf children, 30, 3233, 33, 3537, 4041telephone typewriter (TTY), 4345, 44tests for hearing loss, 2527, 26tinnitus, 2425tuning forks, 25, 27tympanic cavities, 15, 16tympanic membranes. See eardrums

vestibular systems, 19vocalizing, 35, 4041

VPAD+ (videophone), 53

Weitbrecht, Robert, 43Whitestone, Heather, 28, 29, 45


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About the AuthorHenry Wouk is a writer who lives in Western Massachussetts. He has authored more than a dozen books on health and science and has written articles for a variety of national magazines.

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Title PageCopyrightContentsChapter 1 - What Is It Like To Have A Hearing Disorder?Chapter 2 - What Are Hearing Disorders?Chapter 3 - The History Of Hearing DisordersChapter 4 - Living With A Hearing DisorderGlossaryFind Out MoreIndex

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