A hearing impairment is defined by the Individuals with Disabilities Education Act (IDEA) as "an impairment in hearing, whether permanent or fluctuating, that adversely affects a child's educational performance but that is not included under the definition of deafness. Deafness is defined as: a hearing impairment that is so severe that the child is impaired in processing linguistic information through hearing, with or without amplification, that adversely affects a child's educational performance
Types of Hearing Loss
There are four basic types of hearing loss:
- Conductive hearing loss
Conductive hearing loss occurs when sound waves are not transmitted effectively to the inner ear because of some interference in:
- The external ear canal;
- The mobility of the eardrum which can be caused by the accumulation of fluid in the eustachian tube which connects the middle ear to the back of the throat;
- The three tiny bones inside the middle ear;
- The middle-ear cavity;
- The openings into the inner ear;
- The eustachian tube;
Modern techniques make it possible to cure or to improve many cases involving problems with the outer or middle ear. Individuals with conductive hearing loss can often benefit greatly from medical intervention and/or the use of a hearing aid.
- Sensorineural hearing loss
With the sensorineural hearing loss, the damage lies in the inner ear, the auditory nerve, or both.
The cochlear, which is the innermost portion of the ear, has approximately 30,000 hearing nerve endings (hair cells). The hair cells in the large end of the cochlea respond to very high-pitched sounds, and those in the small end (and throughout much of the rest of the cochlea) respond to low-pitched sounds. These hair cells, and the nerve that connects them to the brain, are susceptible to damage from a variety of causes.
- When there is damage to any part of the cochlea, the term "sensory" hearing loss is used.
- "Neural" hearing loss is the correct term to use when the damage is to the auditory nerve, anywhere between its fibers at the base of the hair cells and the relay stations in the brain.
- Central hearing loss
In central hearing loss, the problem lies in the central nervous system, at some point within the brain. Comprehending speech is a complex task. Some people can hear volume perfectly well, but have trouble understanding what is being said. Although information about central hearing loss is accumulating, it remains somewhat a mystery in otology (the medical specialty of ear medicine and surgery).
A condition called central auditory processing disorder frequently leads people to think they have hearing loss when their hearing sensitivity is actually normal. Despite the fact that this problem is extremely common and present in many highly successful people, it can present challenges in a classroom environment.
- Mixed hearing loss
A mixed hearing loss occurs when an individual has both a conductive and sensorineural hearing loss in the same ear.
This type of hearing loss is a result of perceptual deficits rather than a physiological cause, and can be the result of an emotional trauma. Hearing Loss in One Ear (Unilateral Hearing Loss)
A unilateral hearing loss refers to hearing loss in one ear only which can range from mild to total hearing loss in that ear. In the case of a unilateral hearing loss, a child can hear well in most situations. Problems may be experienced in the following instances, however:
- Hearing sounds directed at the affected ear
- Localizing the source of sounds that are hear
- Understanding speech in a noisy background (this is more problematic if the good ear is close to the noise.
A unilateral hearing loss can impact a child's school performance. There is research that shows that 25%-35% of children with unilateral hearing loss are a risk for failing a grade in school. They may show a limited attention span, be distractible or experience fatigue as the school day progresses. A child's teacher should always be made aware of a unilateral hearing loss so that necessary accommodations can be made and the child's performance can be monitored.
Modes of Communication
Communication access is the foundation for learning. Students with hearing impairment will develop their mode of communication within their family unit. This may be a manual form of communication such as American Sign Language or a variant of oral communication. Both require training and support for the parents and child. According to the Operating Standards for Ohio's Schools Serving Students with Disabilities, parents of students with hearing impairments can choose their child's mode of communication for educational purposes. This decision is included in the child's Individual Education Program and becomes the language of instruction for that student.
There are two main communication modes and the decision regarding the use of each is based on a number of factors including degree of hearing loss, age of the onset of the hearing loss, parental choices, and learning styles.
Strategies available to Deaf/hard of hearing students can be broken down into two general categories.
- Sign Language
- Speech/Oral Communication
Signed speech can include:
- ASL (American Sign Language)
- is a communication system that incorporates the use of the hands, arms, body and face to produce a language with its own grammar and linguistic rules.
- MCE (Manually Coded English)
- is a mixed language system used in communication between Deaf and hearing individuals where some signs may be compromised when there is no ASL equivalent to the spoken word or vice versa. It was developed to code English word order, syntax and grammar. While it was developed to ease the transition from written English to speech, it does not keep up with spoke English as ASL does.
- Cued Speech
- A system of phonemically-based handshapes used to supplement speechreading. It uses eight handshapes to represent consonants and four positions on the face to signify vowels to aid speechreaders in distinguishing between words that look the same on the lips such as pat and mat.
This refers to the use of speechreading and auditory cues for English communication. For Deaf individuals who have very little auditory ability, oral communication requires extensive training and speech therapy. Only 30-40% of all speech sounds can be read on the lips and a number of common conditions impede the process of speechreading, including: poor lighting, use of unfamiliar names or words, rapid speech, overlapping speakers, etc.
Every student has his/her own unique needs. Many hard of hearing students will rely on speech/oral and text communication with the assistance of a hearing aid and/or other assistive technology and through the use of speechreading. These individuals may or may not choose sign language as their mode of communication. Students with moderate hearing loss (65-95 decibels) or a profound loss (over 95 decibels) are more likely to use sign language, although some individuals with moderate and profound loss will choose oral communication. There are schools for the Deaf that focus on oral communication. Two such schools in Ohio are Ohio Valley Voices and St. Rita's School for the Deaf.
Hearing aids: Proper functioning of hearing aids is addressed in Title 34, Code of Federal Regulations: Sec. 300.303 Proper functioning of hearing aids which reads: "Each public agency shall ensure that the hearing aids worn in school by children with hearing impairments, including deafness, are functioning properly. (Authority: 20 U.S.C. 1412(a)(1))" Local school district do not usually provide hearing aids for students, however, they bear the responsibility of ensuring that a child's hearing aids are in proper functioning order.
Classroom Supports For Students With Hearing Impairments
- Interpreter Services
Ohio's deaf and hard of hearing students often require the services of a qualified educational interpreter to gain access to and benefit from participation in the general education curriculum. Under IDEA, parents have the right to choose a child's mode of communication and the school has a responsibility to address that need. Parents may request American Sign Language, Manually Coded English or an oral program for their child. If interpreter services are required to support a student in classes or in extracurricular activities sponsored by the school district, the district is responsible for providing the services.
"Interpreter services includes assisting learners with hearing impairments and deaf learners by providing interpretation in English and American Sign Language, transliteration in a manual form of coded English or other coded forms of English." [Sec. 3301-51-01(JJ)(h) Operating Standard for Ohio's Schools Serving Student To find out about interpreter services and requirements for interpreters, parents may contact the Interpreter and Sign Language Resource Center, Ohio School for the Deaf at 614-995-1566.
- Assistive Technologies in the Classroom
A range of assistive technologies can be used in the classroom to support the education of students with hearing impairments.
Other technologies used in the classroom would be identified by the IEP team and can include:
- Captioned Media
- Captioned Media is a free service funded by the U.S. Department of Education that loans captioned videos and DVD's to deaf and hard of hearing individuals, their families and teachers, interpreters and anyone who works with deaf or hard of hearing persons. There are no charges for postage. A catalog of available items is available on the internet of by catalog. The user must register and request an account to participate.
- The Sound Field System
- A sound field system consists of a microphone that the teacher uses that is connected to speakers mounted in the room to help students hear the teacher above the ambient classroom noise. They can be important for some students with mild hearing impairments and in improving the achievement of other children in the classroom. Some research has been done regarding sound field systems. Following is the introduction to Sound Field Systems by two researchers.
- Rehabilitation Engineering Research on Hearing Enhancement
- Classroom sound-field systems are basically Public Address (PA) systems with the inclusion of a wireless microphone. As the teacher talks into the microphone his/her voice is transmitted to a specialized receiver/amplifier that is connected to, or physically a component of, a loudspeaker assembly. The loudspeakers may be located in the ceiling, on the walls around the room, or at the room corners. Whatever arrangement is used, the purpose of the system is to ensure that the teacher's voice is clearly audible above the background sounds at all instructional locations within the room. Research has shown that in the average classroom, the teacher's voice usually arrives at the children at a level only 6 dB or so above the background sounds. (Mark Ross, Ph.D. and Harry Levitt, Ph.D., retrieved, February 4, 2005)
- FM System
- FM or frequency modulated systems, also called auditory trainers, consist of a microphone that the teacher uses to transmit his/her voice directly to a student who is using a receiver. The receiver can be a small amplifier at the student's desk, or to headphones or transmitted directly to the student's hearing aid. Wherever the teacher stands or the direction the teacher faces, the student is able to hear the teacher's voice at the same level above ambient room noise.
- Communication Access Realtime Translation (CART) is a transcription system that provides a word-for-word translation of everything that is said is settings such as courtroom, classrooms, churches, meetings or conferences. CART captions can be displayed on a computer for one person to read, or it can be projected to a large screen or broadcast via satellite or the internet. A trained transcriber must be used to provide this service.
- TypeWell is a transcription system that is used as a realtime communication access or notetaking service provided by a TypeWell-trained transcriber. The transcriber does not Type word-for-word, but is trained to capture the meaing of what is said as weel as how it is said. Students read on a computer the notes as the transcriber writes. Students can also type questions and comments to the transcriber for clarification. Transcriber notes can be used as notes after the class.
- Voice-to Text-to-Sign Language Technologies
- Voice-to and Text-to-Sign Language technologies offer the promise of real time sign language interpretation using technology, however, the accuracy of the interpretation is not high enough for consistent use at this time. All of these products, whether voice-to-text or voice-to-sign language depend upon voice recognition and the software programs must be trained for a specific speaker. Accuracy rates are higher in a quiet environment limiting practical application classroom.
A cochlear implant is a small, complex electronic device that can help to provide a sense of sound to a person who is profoundly deaf or severely hard of hearing. The implant is surgically placed under the skin behind the ear.
An implant has four basic parts: microphone, which picks up sound from the environment; a speech processor, which selects and arranges sounds picked up by the microphone; a transmitter and receiver/stimulator, which receive signals from the speech processor and convert them into electric impulses; and electrodes, which collect the impulses from the stimulator and send them to the brain.
More children with hearing losses are getting cochlear implants at early ages each year. A student's IEP team must consider the special needs of a child with a hearing loss who has a cochlear implant, whether they be continued interpreter services, auditory training support, and/or tutoring services for academic subjects. Each child's needs will be different.
An implant does not restore or create normal hearing. Instead, under the appropriate conditions, it can give a deaf person a useful auditory understanding of the environment and help him or her to understand speech.