Sensory Disability

Sensory disability is a disability resulting from the impairment of one of the senses, generally vision and hearing. These include visual and hearing impairments which refer to mild to severe loss of hearing or vision or both hearing and vision (UNESCO, 2009).

Visual impairment is a broad term used to describe the complete or partial loss of vision. It has both legal and educational definitions. The legal definition defines blindness as having a distance visual acuity of 20/200 or less with the best possible correction whereas partially sighted has visual acuity of 20/70. A visual acuity of 20/200 implies that a person who is legally blind can see at twenty feet, what a person with normal vision can see at a distance of two hundred feet; while a visual acuity of 20/70 means a persons who is partially sighted can see something at 20 feet what a normal vision can see at 70 feet (Mastropieri and Scruggs, 2000; Ashman and Elkins, 1998). On the other hand, educational definition involves processing of information specifically reading. For example, students with visual impairment may be assessed based on visual acuity but may each learn and function in different manner. According to Gargiulo (2012), students with low vision are capable to read using enlarged prints. Others are functionally blind that the primary mode of learning is through tactile or auditory mean like Braille.

The greatest challenges most persons with visual impairment face are difficulties in mobility; understanding and using non-verbal communication; and difficulties with written communication.

It is also important to note that individuals who are born blind (or with little residual vision), or who lost their vision at a very early age have relatively different needs, and face different barriers, than individuals who have lost their vision fully or partially later during their childhood.

Hearing impairment on the other hand is a general term to refer the total or partial loss of hearing. Hard of hearing is described as the partial loss of hearing while deafness is used to describe total or complete loss of hearing (UNESCO, 2009). According to Gargiulo (2012), persons who are hard of hearing are those whom the sense of hearing is defective but functional, either with or without hearing aid, for the purpose of processing linguistic information. Deafness on the other hand means the sense of hearing is non-functional for the ordinary purpose of life. It prohibits successful processing of linguistic information through hearing, with or without hearing aid. 

Hearing may be impaired in terms of the range of frequencies one can hear or the volume of sound, or the combination of both. As loss becomes greater, it has corresponding effect upon language and speech development as well as academic achievement in school.

Hearing impairment can differ in degree from mild to profound (Frederickson and Cline, 2009; Ashman and Elkins, 1998). A mild hearing impairment means having a BEA or Better Ear Average (the softest sound that can be heard) of 30-40 decibels (dB) of sound. A person affected may fail to realize being addressed by another person and may have some difficulty in conversation. Persons with moderate hearing impairment may have difficulty hearing at a distance and in noise. They can hear 40-65 dB of sound and may benefit from using hearing aid. Severe hearing impairment involves having a BEA of 65-96 decibels. In this case, normal conversation is almost impossible and may find the use of hearing aid quite useful. Lastly, individuals with profound hearing impairment can hear 95 and above decibels. Normal conversation is impossible for these individuals. They mainly depend on visual cues to communicate such as sign language.

The greatest challenge persons with hearing impairment face is difficulties with communication. This is so because the majority of the population uses oral communication. People with hearing impairment practice oral or manual means of communication, or a combination of both. Oral communication includes speech (vocal communication), lip-reading and the use of residual hearing, while manual communication includes sign language and fingerspelling. Total communication is a combination of oral and manual communication.

It has to be emphasized that both visual and hearing impairment do not affect a person's intellectual capacity or ability to learn. They are not a disadvantage if the educational, social and attitudinal structures of society enable them to learn and achieve their potential based on their unique needs and mode of learning. 

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