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1) Causes of Hearing Loss
Hearing is the ability to perceive sound in the surrounding through air. Hearing loss exists when a person cannot hear sound or understand the content of the sound. The term could be abbreviated as HL.
1. According to the time that hearing loss occurs, it could be divided into two categories:
| The time that hearing loss occurs |
| Congenital hearing loss |
Acquired hearing loss |
| Congenital hearing loss is hearing loss present either during pregnancy or at the time of birth due to virus infection or other factors. |
Acquired hearing loss is hearing loss that appears after birth as a result of various factors. |
| Causes of hearing loss |
| 1. |
Maternal infections of German measles and syphilis. |
| 2. |
Rh incompatibility between the Rh factor in the blood of the baby and its mother. |
| 3. |
Perinatal asphyxia or brain trauma. |
| 4. |
neonatal jaundice, erythroblastosis fetalis, otosclerosis, etc. |
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| 1. |
Impaired from diseases: meningitis, otitis media, pneumonia, measles and chickenpox. |
| 2. |
Impaired because of external reasons: accidental head injury, noise pollution, medications, psychological stress, etc. |
| 3. |
Aging. |
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2. Depending on the nature of the disorder from the medical perspective, it could be categorized as:
| Depending on the nature of the disorder from the medical perspective |
| Sensorineural hearing loss |
Conducive hearing loss |
| It occurs because of damage to the cochlea or the vestibulocochlear nerve before, during or after birth. |
It occurs when there is a problem conducting sound waves to the cochlea. |
| Causes of hearing loss |
| Congenital |
Acquired |
Congenital |
Acquired |
| 1. |
Hereditary:
genetic defects |
| 2. |
Nonhereditary
- measles
- Kernicterus
- birth injury
- drug poisoning
- congenital syphilis |
|
| 1. |
presbycusis |
| 2. |
head injury |
| 3. |
drug poisoning |
| 4. |
noise induced hearing loss |
| 5. |
hearing loss caused by metabolic disorders |
| 6. |
tumor |
| 7. |
lymphoedema |
|
| 1. |
external auditory canal atresia |
| 2. |
congenital stapes fixation |
| 3. |
congenital malleus fixation |
| 4. |
ossicular disruption or dysplasia |
| 5. |
primary sideroblastic anemia |
|
| 1. |
external auditory canal occlusion |
| 2. |
tympanic membrane perforations |
| 3. |
serous otitis media |
| 4. |
adhesive otitis media |
| 5. |
ossicular disruption or wound |
| 6. |
cholesteatoma |
| 7. |
tympanosclerosis |
| 8. |
fixation of the ossicular chain |
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Reference:
- DeWeese, D.D., Schuller, D.E. and Schleuning, A.J., 1992, Deweese and Saunders' Otolaryngology (Y.Y. Chiu & T.H. Lin, Trans.). New Taipei City: Ho-Chi Publishing.
- http://www.cnad.org.tw
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2) Types of Hearing Loss
Degree of hearing loss is influential on one's verbal communicative skills. If measured in an objective manner, it could be used as an important basis for educational placement, curriculum design, application of teaching methods, and the training of verbal and auditory skills. The measurement of hearing loss range, however, is bound to differ according to different needs. Currently, the classification is conducted in accordance to the "Enforcement Rules of the Special Education Act" and the "People with Disabilities Rights Protection Act".
1. Pursuant to Article 18 of the "Enforcement Rules of the Special Education Act",
hearing loss is divided into four types base on the better ear:
| Type of hearing loss |
Hearing loss range (dB) |
| Mild loss |
40(dB)> mild loss >25(dB) |
| Moderate loss |
60(dB)> moderate loss >40(dB) |
| Severe loss |
90(dB)> severe loss >60(dB) |
| Completely deaf |
completely deaf >90(dB) |
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2. Pursuant to "People with Disabilities Rights Protection Act",
namely the act for people with disabilities rights, hearing loss could be divided into three types:
| Type of hearing loss |
Hearing loss (dB) |
Level of hearing loss |
| Mild loss |
Hearing loss of 55-69 dB
in the better ear |
People with balance disorders
and difficulty in walking |
| Moderate loss |
Hearing loss of 70-89 dB
in the better ear |
People with balance disorders
and difficulty in standing up |
| Severe loss |
Hearing loss of 90 dB or more
in the better ear |
People with balance disorders
and difficulty in sitting |
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Reference:
- http://disable.yam.org.tw/
- http://edu.law.moe.gov.tw/
- http://163.32.59.168/2/org/Spedu/01.pdf
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