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Intensity, or loudness, is measured in decibels (dB). A person with hearing within the normal range can hear sounds ranging from 0 to 140 dB. A whisper is around 30 dB. Conversations are usually 45 to 50 dB. Sounds that are louder than 90 dB can be uncomfortable to hear. A loud rock concert might be as loud as 110 dB. Sounds that are 120 dB or louder can be painful and can result in temporary or permanent hearing disability. Impairments in hearing can happen in either frequency or intensity, or both. Hearing disability severity is based on how well a person can hear the frequencies or intensities most often associated with speech. Severity can be described as mild, moderate, severe, or profound. The term “deaf” is sometimes used to describe someone who has an approximately 90 dB or greater hearing disability or who cannot use hearing to process speech and language information, even with the use of hearing aids. The term “hard of hearing” is sometimes used to describe people who have a less severe hearing disability than deafness. Hearing disability can affect one or both ears. A loss that affects one ear is called a unilateral loss. A loss that affects both ears is called a bilateral loss. There are four main types of hearing disability: Conductive: Hearing disability caused by a problem in the outer ear or middle ear. Conductive losses usually affect all frequencies to the same degree. These losses are not usually severe. Sensor neural: Hearing disability caused by a problem in the inner ear or auditory nerve. A sensor neural loss often affects a person’s ability to hear some frequencies more than others. This means that sounds may be appear distorted, even with the use of a hearing aid. Sensor neural losses can range from mild to profound. Mixed: A combination of conductive and sensor neural losses. Central: Hearing disability caused by a problem along the pathway from the inner ear to the auditory region of the brain or in the brain itself. Approximately 30% of children who are deaf or hard of hearing also have one or more other developmental disabilities, such as mental retardation, cerebral palsy, vision impairment, or epilepsy. Hearing disability can affect a child’s ability to learn both to speak and to understand spoken language. This is especially true if the child is born with a hearing disability or loses his or her hearing before 2 years of age. People with hearing disability may communicate using speech (sometimes called oral communication), sign language (sometimes called manual communication), or a combination of both. Oral communication focuses on speech, listening with hearing aids, and sometimes lip-reading. Manual communication includes sign language. You can learn more about the following questions about hearing disability below: How common is hearing disability? What causes hearing disability? Can it be prevented? What is the cost or economic impact associated with hearing disability? What resources are available for people with hearing disability and their families? How can we improve the health of people with hearing disability? How can kids learn about hearing disability? Where can I go to learn more about hearing disability? What causes hearing disability? Can it be prevented? Normal hearing requires that all parts of the auditory pathway are working correctly. This pathway includes the external ear, middle ear, inner ear, auditory nerve, and the connection between the auditory nerve and the brain. The exact location and nature of the problem in the auditory pathway determines the type and severity of a person’s hearing disability. Some causes of hearing disability occur before a baby is born. These include genetic disorders (such as Waardenburg syndrome or Crouzon syndrome) and infections (such as congenital rubella or congenital syphilis). About half of all cases of hearing disability among children are thought to result from genetic factors. Sometimes these children have a syndrome of which hearing disability is only one feature. However, in most children with hearing disability that is due to a genetic cause, the hearing disability is not part of a syndrome. A variant of the connexin 26 gene is responsible for much of the hearing disability in this latter group of children. Hearing disability can affect a child’s potential to develop speech, language, and social skills. The earlier a child who is deaf or hard of hearing starts getting services, the more likely the child’s speech, language, and social skills will reach their full potential. All newborns should be screened for hearing disability. More and more hospitals are screening babies before they go home. Universal newborn hearing screening programs have three main goals: Babies should be screened before they leave the hospital or before 1 month of age. If a baby does not pass the screening, he or she should get a follow-up evaluation before 3 months. Babies who are deaf or hard of hearing should receive services before they are 6 months old. These services help babies develop speech, language, and social skills. Classifications of hearing disability There are three types of hearing disability: conductive , sensor neural , and mixed . A conductive hearing disability is a result of damage to outer or middle ear. Conductive losses are not severe and often times can be surgically corrected. A person with a conductive loss may reap great benefits from hearing aids. A sensor neural hearing disability is a result of damage to the hair cells of the inner ear or nerves. This type of loss ranges from mild to profound and is permanent. In other words, surgery cannot be performed to correct a sensor neural hearing disability. Often times, hearing aids are not helpful either. While the aids may amplify sounds, the sounds are still distorted. A mixed hearing disability simply means that the hearing problem occurs in the outer or middle ear and inner ear. There are different degrees of hearing disability. Below is a chart that lists and classifies the degrees of hearing disability according the dB range in which sound is heard.
Configurations of hearing disability
Finally, it is important to understand the symmetry of a hearing disability. If a person has the same degree and type of hearing disability and configuration in each ear, the loss is symmetrical. However, if the degree and type of hearing disability and configuration varies or is different in each ear, the loss is classified as asymmetrical. It is important to note that hearing disability affects all individuals differently. While some hearing disabled people may benefit from hearing aids or amplification, others may not. It is extremely important to talk with the hearing disabled person and find out exactly what type of loss they have in order to accommodate their needs. Restrictions of the hearing disability Many individuals with hearing disability face many restrictions when they use technology. Often times hearing impaired people are limited to the amount of technology because it is not accessible. For example, many hearing impaired individuals cannot listen to live voice mail or on-line audio chat because amplification cannot be made loud enough or because the sound is not clear to the listener. Most people believe that if hearing impaired individuals wear hearing aids or other types of amplification that they can hear anything. While hearing aids do help amplify sound, they do not help clarify the sound. To explain, a person who suffers from a nerve damage hearing disability will not fully benefit from hearing aids. The hearing aids will make all sound louder; however, just because the sound level is increased does not mean the hearing impaired person will be able to clearly understand the sound. Hearing aid amplification can be compared to a car radio. In other words, just as the volume control on the radio makes the sound louder, the hearing aid makes the sound louder. However, if the radio is not tuned into a station then it does not matter how loud the sound is because all that is heard is static. This is similar to how some hearing impaired individuals hear. The sound is amplified but not necessarily clear. There is no technology available that can clarify sound for hearing impaired persons. By visiting www.neurophys.wisc.edu/animations/, one can actually listen to what speech and music sound like to a person with normal hearing, moderate hearing disability, or severe hearing disability. These computer generated on-line simulations will help educators and other people who communicate with the hearing impaired understand what struggles a hearing impaired person may encounter when relying on only auditory information. It is important for educators to understand that talking louder or using a microphone will not always be helpful. Most hearing impaired individuals need a text version of any type of auditory presentation. How to make a classroom more accessible for the hearing disability Many educators who use technology within the classroom need to make it more accessible for hearing impaired students. For most students, the World Wide Web has proven to be a wonderful resource for learning and communication. However, some individuals are not able to gain all of the benefits the Web has to offer because of their disability. Many people who are hearing impaired cannot fully participate in the Web's modernized graphics, audio, and video capabilities. To explain, some teachers use multimedia presentations to teach lesson plans. While multimedia presentations can be dynamic they are certainly not fully accessible to most hearing impaired people. For instance, some WWW sites have incorporated short movie or audio clips to their sites. Obviously, without captions or audio descriptions a hearing impaired student is certain to miss the majority of information presented. It is important to realize that captioning has many additional benefits. For instance, some computers are not equipped to produce sound. Therefore when a multimedia presentation is given, the viewer may miss important information that is given auditorally. If captions are present, the viewer is still able to follow the presentation without missing any content. Additionally, captions can also be a remarkable tool for increasing reading skills. Obviously, the more a student is exposed to the written English language, the better their reading skills will be. In addition to providing captioning on multimedia presentations, it is also imperative that educators provide captioned videos, movies, or filmstrips when a hearing impaired student is in the classroom. Most hearing disabled individuals struggle to understand the sound that comes from an audio presentation on videos, movies, or filmstrips. Therefore, the student will ultimately miss much of the important information presented auditorally. The following sources, taken from the book Access for All, provide captioned videos, filmstrips, and movies, which are available on loan to schools. Educators can write to the sources below to obtain information on captioned materials or visit
Additional Assistive Technology
In conclusion, educators must understand what hearing disability is and the restrictions that hearing impaired individual may encounter when using technology. Only once educators fully understand hearing disability can they begin to make their classroom more accessible for hearing impaired students. Teachers must remember that hearing impaired students can flourish in the regular classroom setting if the proper accommodations are made for the student(s). Teachers should make every effort to provide captioning for all presentations, including auditory, visual, or multimedia, given within the classroom. Again, there are many wonderful resources available to assist educators as they adapt their lesson plans to meet the needs of the students in the class.
Links for Hearing
Disability http://www.masterstech-home.com/asldict.html http://www.vanderbilt.edu/BillWilkersonCenter/bwchome.html http://www.deafhealth.net/dhn.htm http://deafness.about.com/health/deafness/ http://www.deafzone.com/index1.html http://www.hearingalliance.com/ http://www.hearingexchange.com/ http://www.hearinghealthmag.com/home.htm http://www.hearinglossweb.com/ http://www.bme.jhu.edu/labs/chb/index.html http://library.thinkquest.org/10202/ |
Hearing
Disability
Before
we can understand hearing disability, we must first understand what hearing
entails. When we hear sounds, we really are interpreting patterns of
movement of air molecules. We can describe sounds in terms of their
frequency (or pitch) and intensity (or loudness). Frequency is measured in
hertz (Hz). A person who has hearing within the normal range, can hear
sounds that have frequencies between 20 and 20,000 Hz. The most important
sounds we hear every day are in the 250 to 6,000 Hz range. Speech includes a
mix of low and high frequency sounds. Vowel sounds like “u” have low
frequencies (250 to 1,000 Hz) and are usually easier to hear. Consonants
like “s,” “h,” and “f” have higher frequencies (1,500 to 6,000 Hz) and are
harder to hear. Consonants convey most of the meaning of what we say.
Someone who cannot hear high-frequency sounds will have a hard time
understanding speech.
Next,
one must understand the configuration of a hearing disability. There are
three types of configurations: rising, sloping, and flat. A rising
configuration means that a person can hear high pitch tones better than low
pitch tones. A sloping configuration means that a person can hear low pitch
tones better than high pitch tones. Finally, a flat configuration means that
a person needs the same amount of loudness to hear a low or high pitched
sound .
Teachers
who have a hearing impaired student may need to use a telecommunication
device when communicating with the student via telephone. Some hearing
impaired individuals are not able to carry on a conversation on a regular
telephone because they cannot adequately hear the conversation. However, a
TDD or TTY machine allows a hearing impaired person to communicate over
telephone lines by typing which produces a printed version of the voice
transmission. A TDD will need to be added to the school if the teacher needs
to communicate with a hearing impaired person over the phone or if the
hearing impaired student needs to use the phone but cannot communicate on a
regular voice telephone while at school. Furthermore, many hearing impaired
students have parents who are hearing impaired of deaf. A TDD may be
essential if the teacher needs to communicate with a parent who has impaired
hearing. Most states are now required to have a relay service for TDD
machines. According to an article entitled, "Technology and Telephone Relay
Service", "a Telephone Relay Service, TRS, is an operator assisted interface
between text terminals and voice terminals. In most TRS calls, a deaf or
hard of hearing person dials a toll free number and requests that a call be
made to a hearing person. The TRS operator places the call on a second line.
The conversation between the text telephone user and the voice party takes
place with assistance of the operator, who speaks the typed messages to the
voice party and types the spoken message to the text telephone user." The
TRS service allows a hearing impaired person to make or receive calls from
hearing people who do not have a TDD phone. 
There
are many other pieces of technology available to assist hearing impaired
students within the regular classroom. These products would help make a
classroom more accessible to a hard of hearing individual. For instance,
speech development software allows persons with a hearing disability to
practice speech with a computer while giving them feedback on their efforts.
Speech recognition software allows a hearing disabled student to understand
most of what a teacher is saying because the micro-computer can print what
is being spoken. An FM auditory training system is one more piece of
equipment that may be a wonderful asset to a hearing impaired student in a
regular classroom. The FM system directly links the student's hearing aid to
a microphone worn by the classroom teacher. The sound is transmitted into a
student's hearing aid. The system allows the student to hear an auditory
presentation at a consistent loudness level from wherever the speaker is
located in the classroom. This system helps to eliminate background noise
like paper shuffling, desks moving, or students talking which may drowned
out the teacher's voice. Other devices, such as, flashing lights or
vibrators are of great importance to hearing impaired people. These types of
devices flash or vibrate when a telephone, doorbell, alarm clock, fire
alarm, tornado alarm sound. Lights have also been manufactured to flash to
alert a hearing impaired student when the class period is over. To obtain
additional information about assistive technology devices, visit the sites
published at the end of this paper which are categorized under assistive
technology.