Levels of hearing loss

There are two general types of hearing loss Conductive and Sensorineural. Conductive hearing loss is caused when something interferes with the transmission of sound from your outer ear to the inner ear. Sensorineural hearing loss is caused when there is a problem with your inner ear, or the pathway from the inner ear to your brain. These two types have different levels of hearing loss measured in decibels:

Conductive hearing losses are due to blockage or damage to the outer or middle ear that prevents some waves from travelling (being conducted) to the inner ear. Generally, someone with a conductive hearing loss has a mild to moderate disability. Some conductive hearing losses are temporary. 

Causes of Conductive Hearing Loss

Conductive hearing loss is caused by a blockage that prevents the conduction of sound from the outer to inner ear. This blockage can be due to one of the following reasons:

a)Infection: The most common cause of conductive hearing loss is fluid in the middle ear. This may be a result of repeated or chronic infection (otitis media).

b)Injury of the outer ear: Holes in the eardrum (tympanic membrane Perforation) and skin cysts (cholesteatoma).

c) Blockage of the ear canal: It may develop as a result of Eustachian tube obstruction (eg, due to allergies) or due to excessive ear wax that plugs the ear canal or other small objects like food, beads or insects. Narrowing of the ear canal can also be due to surgery or disease. 

d) Otosclerosis: It is a condition in which the ossicles of the middle ear become immobile and hence there is a defect in the proper conduction of sound through the middle ear, leading to conductive hearing loss.

e)Congenital (in-born) deformities:  Down syndrome, Franceschetti Syndrome, Treacher Collins Syndrome or Achondroplasia (dwarfism).

Sensorineural Hearing Loss

1)Sensorineural hearing loss occurs when there is damage to the inner ear or the auditory nerve (the eighth cranial nerve), and usually cannot be improved medically or surgically. 

2)Individuals affected by a sensorineural loss are able to hear different frequencies at different intensity levels.

Causes of Sensorineural Hearing Loss

1)The origin of this type of hearing loss, besides the most common reason of noise exposure, is thought to be: 

a) Genetic (runs in the family)

b)Prenatal (occurs in fetus as a result of infection to the mother)

c)Peri-natal (Occurs to the baby during the birth process) e.g.Premature/difficult delivery etc.

d)Acquired e.g. meningitis, physical trauma (accident)

e) Cancer treatments such as  Chemotherapy: The most common types of chemotherapy that cause

hearing loss are the platinum drugs or compounds. 

Early identification and intervention of hearing loss

1)Researchers  found that the group who was diagnosed before 6 months of age exhibited significantly better receptive and expressive language skills than the group who had been diagnosed after 6 months of age.

2) In addition, for normal cognitive development, the finding was evident across all test ages, communications modes, degrees of hearing loss, and socioeconomic strata. 

3)Researchers conducted a longitudinal study to examine the impact of early intervention in the hearing impaired children. Children with severe and profound hearing impairments who were fitted with amplification prior to six months of age displayed communicative and linguistic skills very similar to those of their normally hearing peers. 

4)The primary justification for early identification of hearing impairment in infants relates to the impact of hearing impairment on speech and language acquisition, academic achievement, and social/emotional development. 

5) The goal of early identification and intervention is to minimize or prevent these adverse effects.

6) Significant hearing loss interferes with the development of phonological and speech perception abilities needed for later language learning, e.g., meaningful language at the word, phrase, and sentence levels. These impairments in communication skills can lead to poor academic performance  and ultimately, to limitations in career opportunities.

7)Three laws protect the rights of children to have assistive technology in schools when needed: the Americans with Disabilities Act, Section 504 of the Rehabilitation Act and the Individuals with Disabilities Education Act (IDEA). Each of these laws has provisions for every child to have access to instruction, which for a deaf student would mean the assistive technology necessary for them to learn at the same pace as the rest of the class.