Hearing loss can be caused by many different causes some of which can be successfully treated with medicine or surgery, depending on the disease process. There are 3 types of Hearing loss-
- Conductive hearing loss.
- Sensorineural hearing loss.
- Mixed hearing loss.
Conductive Hearing Loss
Conductive hearing loss occurs when there is a problem transferring sound waves anywhere along the pathway through the outer ear, tympanic membrane(eardrum), or Middle ear (ossicles). If a conductive hearing loss occurs in conjunction with a sensorineural hearing loss. Depending upon the severity and nature of the conductive loss, this type of hearing impairment can often be treated with surgical intervention or pharmaceuticals to partially or, in some cases, fully restore hearing acuity to within normal range. However, cases of permanent or chronic conductive hearing loss may required other treatment modalities such as hearing aid devices to improve detection of sound and speech perception.
Common causes of conductive hearing loss include: –
1. External Ear
- Cerumen (Earwax) or foreign body in the external auditory canal.
- Otitis externa, infection or irritation of the outer ear.
- Exostoses, abnormal growth of bone within the ear canal.
- Tumour of the ear canal.
- Congenital stenosis or atresia of the external auditory canal (narrow or blocked ear canal).
- Ear canal stenosis & atresia can exist independently or may result from congenital malformations of the auricle such as microtia or anotia.
2. Middle Ear
Fluid accumulation is the most common cause of conductive hearing loss in the middle ear, especially in children. Major causes are ear infections or conditions that block the Eustachian tube, such as allergies or tumours. Blocking of the eustachian tube leads to decreased pressure in the middle ear relative to the external ear, and this causes decreased motion of both the ossicles and the tympanic membrane.
3. Inner Ear
Third window effect caused by: Superior canal dehiscence – which may require surgical correction.
Examination of the external ear canal and ear drum is important and may help identify problems located in outer ear up to the tympanic membrane.
Tympanometry or acoustic immittance testing, is a simple objective test of the ability of the middle ear to transmit sound waves from the outer ear to the middle ear and to the inner ear. This test is usually abnormal with conductive hearing loss.
Pure tone audiometry, a standardized hearing test over a set of frequencies from 250 Hz to 800Hz, may be conducted by a medical doctor, audiologist or audiometric with the result plotted separately for each ear on an audiogram. The shapes of the plot reveals the degree and nature of hearing loss, distinguishing conductive hearing loss from other kinds of hearing loss.
SENSORINEURAL HEARING LOSS
Hearing loss caused by damage to the inner ear or the nerve from the ear to the brain. Sensorineural hearing loss is a type of hearing loss or deafness in which the root cause lies in the inner ear or sensory organ or the vestibulocochlear nerve. SNHL accounts for about 90% of reported hearing loss. SNHL is generally permanent and can be mild, moderate, severe, profound, or total. Various other descriptors can be used depending on the shape of the audiogram, such as high frequency, low frequency, U-shaped, notched, peaked, or flat.
Sensorineural hearing loss may be genetic or acquired. People may have a hearing loss from birth or the hearing loss may come on later. Many cases are related to old age.
MIXED HEARING LOSS
Mixed Hearing Loss is a combination of conductive and sensorineural hearing loss, which means there is damage in both the outer or middle ear and in the inner ear. This type of hearing loss ranges in severity from mild to profound. For people with mixed hearing loss, sounds can be both softer in volume and more difficult to understand.
If the hearing loss is mostly conductive speech tends to sounds understandable but only if it’s loud enough and there isn’t too much background noise. If the hearing loss is mostly sensorineural, there may be difficulty understanding speech, even when it seems loud enough.
Depending on the degree and diagnosis of mixed hearing loss, it may be treated with medications, surgery, hearing aids or an implantable bone conduction hearing system.
Baha bone conduction implant: A Baha bone conduction implant is an effective treatment for mixed hearing loss because it totally by passes the conductive element of the hearing loss and needs only to address the sensorineural element. Air conductive and Sensorineural elements.
Specific Learning Difficulties of Hearing Impaired Children: –
The learning difficulties of hearing impairment children lie primarily in their difficulties in speech and language, which may in turn vary according to their degrees of hearing loss. Some of these children may have poor articulations of speech, for example, the omission of high frequency sounds. They may be weak in breath and pitch control and their voices tend to be monotonous. All these make it difficult for them to communicate with other. In language learning they may have difficulties in understanding abstract vocabulary.
Complicated sentence structures and unfamiliar concepts. They may also have difficulties in learning to read and write. Language plays an important part in the higher intellectual development, especially in problem solving. Deafness may cause a language deficit, which in turn affects progress in learning. Many hearing impaired children tend to be rather weak in abstract thinking and analytical power. This can be a hindrance to their acquisition of knowledge.
Objective of the Education of Hearing Impaired Children
The objective of the education of hearing impaired children are:-
- To help hearing impaired children develop their potential to the full by providing them with learning experiences in school.
- To encourage hearing impaired children to use their residual hearing to develop as much language as possible so that they can master adequate communication skills for use in their everyday life.
- To help hearing impairment children grow up well adjusted and independent so that they can integrate into society.
- To help hearing impairment children develop a correct sense of value and citizenship.