|The 5 Senses|
What You Should Known About People with Sensory Impairments?
Students with sensory impairments have vision or hearing disabilities so significant that their education is affected. Their disabilities can be mild, moderate, or severe, and their specialized needs can range from slight to complex. Because school learning relies so heavily on seeing and hearing, students with these disabilities often experience academic problems and need both teacher accommodations and adaptive equipment. Some of the vocabulary used to describe these disabilities is included in the Professional Edge.
Students with visual impairments cannot see well enough to use vision as a primary channel for learning without significant assistance, Some students are considered legally blind, which means that the vision in their best eye, with correction, is 20/200 or less, or their visual field is 20 percent or less. What a person with normal vision could see at 200 feet, these students can see only at 20 feet. Students legally blind because of a limited visual field can see just a 20 percent or less "slice" of what a person with normal vision would see within his or her range of vision (Hardman, Drew, Egan, & Wolf, 1993).
Although the concept of legal blindness is an important one that helps students access special services throughout their lives, a different set of terms is used in schools. For educators, the term blind is generally reserved to describe the few students who have little useful vision. They use touch and hearing for most learning. Most students with visual impairments are partially sighted, meaning that they have some useful vision; their vision is between 20/70 and 20/200, or they have another vision problem that has a serious negative effect on their learning.
Students with hearing impairments cannot hear well enough to use hearing as a primary channel for learning without significant assistance. Because a huge proportion of formal and incidental learning occurs through conversations, formal presentations, and overheard information, and relies on understanding language, many consider hearing impairments primarily language or communication impairments. A small number of students with hearing impairments are deaf. They cannot process linguistic information through hearing, with or without hearing aids. Most students, however, are hard of hearing, meaning that they have some residual hearing that lets them process linguistic information through hearing, usually by using hearing aids or other assistive devices.
To determine the severity of a hearing loss, professionals check the loudness of sounds as measured in decibels (dB) and the pitch or tone of the sound as measured in hertz (Hz). Normal speech is usually in the 55-60 dB range at 500-2000 Hz. In contrast, a whisper is about 15-25 dB, and a rock band plays at about 110 dB. Students with a hearing loss of 25-40 dB are considered to have a mild loss; they might not hear every word in a conversation or might not distinguish between words with similar sounds (breathing, breeding). Those with a loss of 40-60 dB have a moderate loss; they typically cannot hear enough of a conversation to follow it auditorily. Those with 60-80 dB have a severe loss, and those with more than 80 dB have a profound loss. Students with severe and profound hearing losses typically cannot process speech, even when amplification is used. They rely on sight as an alternative means of learning.
Another factor professionals consider in judging the seriousness of a student's hearing loss is when the loss occurred. Students who have been hearing impaired since birth are often at a disadvantage for language learning since they typically did not go through the natural process of acquiring language. These students can speak, but because they learned to talk without hearing how they sounded, their speech may be difficult to understand. They might prefer sign language and an interpreter for communicating with you and others. Students who lose their hearing after they learn language, after about age 5, sometimes experience fewer language and speech difficulties.