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Pathology => Human Diseases => Deafness
Deafness
INTRODUCTION
Deafness, most simply defined as an inability to hear. This definition, however, gives no real impression of how deafness affects function in society for the hearing-impaired person. Approximately 20 million United States citizens have a hearing impairment. This condition affects all age groups, and its consequences range from minor to severe. Of these 20 million persons, more than 2 million are considered profoundly deaf. That is, they have a hearing loss so severe that they cannot benefit from mechanical amplification, whereas hard-of-hearing persons often can benefit, to varying degrees, from the use of such amplification.
KINDS AND CAUSES
Four types of hearing loss may be described. The first, conductive hearing loss, is caused by diseases or obstruction in the outer or middle ear and usually is not severe. A person with a conductive hearing loss generally can be helped by a hearing aid. Often conductive hearing losses can also be corrected through surgical or medical treatment. The second kind of deafness, sensorineural hearing loss, results from damage to the sensory hair cells or the nerves of the inner ear and can range in severity from mild to profound deafness. Such loss occurs in certain sound frequencies more than in others, resulting in distorted sound perceptions even when the sound level is amplified. A hearing aid may not help a person with a sensorineural loss. The third kind, mixed hearing loss, is caused by problems in both the outer or middle ear and the inner ear. Finally, central hearing loss is the result of damage to or impairment of the nerves or nuclei of the central nervous system.
Deafness in general can be caused by illness or accident, or it may be inherited. Continuous or frequent exposure to noise levels above 85 dB can cause a progressive and eventually severe sensorineural hearing loss.
EDUCATION AND TRAINING
Until the Middle Ages, most people believed that deaf persons were incapable of learning language or of being educated in any way. By the 16th century, however, a few philosophers and educators began to reconsider the condition of deaf persons. A Spanish Benedictine monk, Pedro de Ponce, is considered the first teacher of deaf students, and in 1620 Juan Paulo Bonet, another Spaniard, wrote the first book on educating deaf persons. The book contained a manual alphabet similar to the one used today.
In the 18th century schools were established for deaf children in France by Abbé Charles Michel de l'Épée and, in Germany, by the educator Samuel Heinicke. The conflict that exists to this day as to whether deaf children should be educated by oral (lipreading and speech) or manual (signs and finger spelling) methods dates from this time. The Abbé de l'Épée was a manualist and Heinicke an oralist; each knew of and studied the other's methods.
The first U.S. school for deaf children, still in existence, was established in 1817 by Thomas Hopkins Gallaudet, Laurent Clerc, Mason F. Cogswell, and a group of other concerned persons in Hartford, Connecticut. Gallaudet first went to England and then to France to study the educational methods being used there. When he returned to Hartford, he brought with him Clerc, a deaf French teacher, who became the first deaf teacher of deaf children in the United States. Gallaudet's youngest son, Edward Miner Gallaudet, became the first superintendent of the Columbia Institution for the Deaf and the Dumb and the Blind in Washington, D.C. In 1864 this institution established a collegiate division that would later be known as Gallaudet University in honor of Thomas Gallaudet. Gallaudet University continues to be the only liberal arts college for deaf students in the world. The National Technical Institute for the Deaf, which opened in 1968 in Rochester, New York, offers technical education programs for deaf students. It is the only technical institution in the world for the deaf.
Deafness does not affect a person's intellectual capacity or ability to learn. A child who sustains a hearing loss early in life, however, may lack the language stimulation experienced by children who can hear. A delay in learning language may cause a deaf child's academic progress to be slower than that of hearing children. The academic lag tends to be cumulative, so that a deaf adolescent may be four or more grade levels behind his or her hearing peers. Deaf children who receive early language stimulation through sign language, however, generally do well academically.
Today, by the age of four or five, most deaf children are enrolled in school on a full-day basis. Approximately one-third of the population of school-age deaf children attend private or public residential schools. The rest live at home and attend day programs in schools for the deaf or special day classes in regular schools. Deaf children in public schools may receive instruction exclusively with other deaf children, but increasing numbers of deaf children are being placed in regular classes with hearing children for physical education, vocational training, and one or more school subjects. Some deaf children do most or all of their schoolwork in regular classes, occasionally with the use of interpreters and with periodic assistance from special teachers of the deaf.
COMMUNICATION SYSTEMS
Increasingly, the philosophy of total communication is being used in schools and classes for deaf children. This philosophy encourages the combined use of whatever communication methods are appropriate to the deaf child, including speech, lipreading, American Sign Language, Manually Coded English, Cued Speech, finger spelling, art, electronic media, mime, gesture, and reading and writing.
Finger spelling is a system in which hand shapes and positions correspond to the letters of the written alphabet. In a very real sense, finger spelling can be called "writing in the air."
American Sign Language (ASL) is a language based on gestures and grammatical rules that share some common points with English. The signs in ASL are wordlike units with both concrete and abstract meanings. Signs are made by either one or both hands, which assume distinctive shapes and movements. Spatial relations, directions, and orientation of the hand movements, as well as facial expressions and body movement, make up the grammar of ASL. A number of manual communication systems use the sign vocabulary of ASL in combination with other hand movements to approximate the syntax and grammar of Standard English.
Cued Speech is a system in which eight hand movements indicate the pronunciation of every syllable being spoken. It is a speech-based method that supplements lipreading.
Oral communication is the term used by educators to denote the teaching of speech as an expressive skill to deaf children. It means that speech and lipreading are the only means of communication used for the transmission of thoughts and ideas.
WORK PROSPECTS
Increasing numbers of deaf students are pursuing postsecondary educational programs. In addition to Gallaudet College and the National Technical Institute for the Deaf, more than 60 U.S. colleges have special provisions and programs for deaf students.
Today deaf persons are employed in almost every known vocation, except those where good hearing is an obvious requirement-for example, a commercial pilot or a symphony conductor. Deaf people are doctors, lawyers, teachers, and members of the clergy, as well as secretaries, accountants, chemists, farmers, and laborers. Discrimination does exist, as it does for other minority groups, but employers increasingly are hiring deaf persons and making adjustments for them, such as adding special telephone devices or providing secretary-interpreters or other accommodations that enable the deaf employee to function effectively on the job. Compared with the general population, however, a large percentage of deaf people continue to be unemployed or underemployed.
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