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Why "Universal Design"
Understanding the Population
People who could benefit from more universal designs include many both with
and without disabilities.
In some cases, people may experience difficulty in using products purely as
a result of the environment or an unusual circumstance.
Beneficiaries of universal design include:
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People in a noisy shopping mall who cannot hear a
kiosk
·
People who are driving their car who must operate
their radio or phone without looking at it
·
People who left their glasses in their room
·
People who are getting older
·
People with disabilities
·
Almost anyone
To design for the general population
It is important to understand the diversity, problems, tools, and abilities
of its members.
Categories of Disabilities
Visual Impairments
There are an estimated 8.6 million people with visual impairments (3.4% of
the U.S. population). In the elderly population the percentage of persons with
visual impairments is very high.
Legally Blind
Visual acuity (sharpness of vision) is 20/200 or worse after correction
Field of vision is less than 20 degrees
There are approximately 580,000 people in the U.S. who are legally blind.
Low vision
includes (after correction) problems such as
dimness of vision
haziness
film over the eye
foggy vision
extreme near- or farsightedness
distortion of vision
spots before the eyes
Hearing Impairments
One of the most prevalent chronic disabilities in the U.S.
Approximately 22 million people in the U.S. (8.2%) have hearing
impairments.
Of those, 2.4 million have severe to profound impairments.
Deafness
An extreme inability to discriminate conversational speech through the ear.
Deaf people are those who cannot use their hearing for communication.
Usually, a person is considered deaf when sound must reach at least 90
decibels (5 to 10 times louder than normal speech) to be heard, and even
amplified speech cannot be understood.
Hard of Hearing
People with a lesser degree of hearing impairment
Loss of hearing acuity is part of the natural aging process.
23% of those aged 65 to 74 have hearing impairments and almost 40% over age
75 have hearing impairments.
The number of individuals with hearing impairments will increase with the
increasing age of the population and the increase in the severity of noise
exposure.
Two Types of Hearing Impairment
Sensorineural hearing loss
involves damage to the auditory pathways within the central nervous
system, beginning with the cochlea and auditory nerve, and including the
brain stem and cerebral cortex.
Conductive hearing loss
Damage to the outer or middle ear which interferes with sound waves
reaching the cochlea. Causes include heredity, infections, tumors, accidents
and aging (presbycusis, or "old hearing").
Physical Impairments
Problems faced by individuals with physical impairments include:
poor muscle control
weakness and fatigue
difficulty walking, talking, seeing, speaking, sensing or grasping (due
to pain or weakness)
difficulty reaching things
difficulty doing complex or compound manipulations (push and turn).
inablity to use limbs
Problems (Cont.)
Twisting motions may be difficult or impossible for people with many types
of physical disabilities (including cerebral palsy, spinal cord injury,
arthritis, multiple sclerosis, muscular dystrophy, etc.).
Assistive Devices
Some people must rely on assistive devices which take advantage of their
specific abilities
Commonly used assistive devices include :
mobility aids (e.g., crutches, wheelchairs)
manipulation aids (e.g., prosthetics, orthotics, reachers)
communication aids (e.g., single switch-based artificial voice)
Computer/device interface aids (e.g., eyegaze-operated keyboard) .
Types of Physical Impairments
Neuromuscular impairments
paralysis
weakness
interference with control, via spasticity
Skeletal impairments
joint movement limitations (either mechanical or due to pain)
small limbs
missing limbs
abnormal trunk size
Causes of Physical Impairments
Arthritis
Cerebral Palsy (CP)
Spinal Cord Injury
Head Injury (cerebral trauma).
Stroke (cerebral vascular accident; CVA).
Loss of Limbs or Digits (Amputation or Congenital)
Parkinson's Disease
Causes of Physical Impairments
Multiple Sclerosis (MS)
ALS (Lou Gehrig's Disease)
Muscular Dystrophy (MD)
Cognitive/Language Impairments
There are very few assistive devices for people with cognitive impairments.
Simple cueing aids or memory aids are sometimes used.
As a rule, these individuals benefit from use of simple displays, low
language loading, use of patterns, simple, obvious sequences and cued
sequences.
Cognitive/Language Impairments
Mental Retardation.
A person is considered mentally retarded if they have an IQ below 70 and
if they have difficulty functioning independently.
About 3% of Americans are mentally retarded.
Causes include: infections, Down Syndrome, premature birth, birth trauma,
or lack of oxygen may all cause retardation.
Language and Learning Disabilities
Aphasia, an impairment in the ability to interpret or formulate language
symbols as a result of brain damage.
Specific learning disabilities are chronic conditions of presumed
neurological origin which selectively interfere with the development,
integration, and/or demonstration of verbal and/or non-verbal abilities.
Many people with learning disabilities are highly intelligent aside from
their specific learning disability. 1-8% of school-aged children and youth
have specific learning disabilities.
Age-Related Disease
Alzheimer's disease is a degenerative disease that leads to progressive
intellectual decline, confusion and disorientation.
Dementia is a brain disease that results in the progressive loss of mental
functions, often beginning with memory, learning, attention and judgment
deficits.
The underlying cause is obstruction of blood flow to the brain. Some
kinds of dementia are curable, while others are not.
Seizure Disorders
Epilepsy is a chronic neurological disorder.
It is reported that approximately 1 person in 15 has a seizure of some
sort during his life, and between .5% and 1.5% of the general population
have chronic, recurring seizures.
Seizures can vary from momentary loss of attention to grand mal seizures
which result in the severe loss of motor control and awareness.
Multiple Impairments
It is common to find that whatever caused a single type of impairment also
caused others.
Deaf-blindness is one commonly identified combination.
People with developmental disabilities may have a combination of mental
and physical impairments that result in substantial functional limitations
in three or more areas of major life activity.
Diabetes, which can cause blindness, also often causes loss of sensation
in the fingers. (Impossible to read Braille)
Cerebral palsy is often accompanied by visual impairments, by hearing and
language disorders, or by cognitive impairments.
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