Assistive Technology for Individuals with Sensory Impairments – Vision and Hearing : Assistive Technology for Individuals with Sensory Impairments – Vision and Hearing
Vision : Vision
Vision Demographics : Vision Demographics 15% Americans age 45-64
17% Americans age 65-74
26% Americans age 75+ report some form of vision impairment
All but 2% of this group report that they are partially sighted rather than totally blind
Vision Demographics : Vision Demographics .6% of persons under 18 years of age are visually impaired (approximately 450,000 children and youth)
Vision Demographics : Vision Demographics By Categories
Severe vision impairment – 1.8 million
Low vision – 3 million
Legally blind – 1.3 million
Light perception or less – 260,000
Causes of blindness include glaucoma, macular degeneration, cataract, optic nerve atrophy, diabetic retinopathy, retinitis pigmentosa (51%)
Components of the Visual System : Components of the Visual System Visual Acuity – Clarity of vision
Expressed by notation that describes the size of a visual target and the distance at which the target is identified. 20/20 20/70 20/200 Partially Sighted Legally Blind Light Perception No Light Perception
Slide 7: Visual Field
Areas in which objects are visible to the eye without a shift in gaze
Problems that can occur
Decreased vision in either central or peripheral field
Blind spots
Field cuts
Slide 8: Cataracts
Glaucoma
Slide 9: Macular Degeneration
Retinopathy
Slide 10: Oculomotor Functioning
Concerns the functioning of eye muscles that enable eyes to move together smoothly in all directions
Conditions include:
Strabismus – inability to maintain eyes in a position of binocular fixation due to weak eye muscles causing eyes to cross or diverge
Nystagmus – involuntary movement of the eyes causes problems with acuity
Slide 11: Light and Color Sensitivity
Different vision conditions require adjustment of lighting up or down
Color perception can be impaired – inability of the eyes to interpret particular wavelength frequencies (most common is confusion of red and green)
Slide 12: Color Blindness: Simulation Map of Hurricane Isabel (with color)
Slide 13: Color Blindness: Simulation Map of Hurricane Isabel (simulating red/green colorblindness) Simulated using Vischek (http://www.vischeck.com/vischeck/vischeckURL.php )
Slide 14: Color Blindness: Simulation Subway map
Slide 15: Color Blindness May change color settings in browser
Approximately 8-10% of the male population and about 0.5% of the female population experiences some form of color deficiency
Cell phone, PDA and text browser users may not have color Reds & greens are often indistinguishable
Other colors may be indistinguishable
Assistive Technology for Vision Impairments : Assistive Technology for Vision Impairments For those who have some vision skills remaining
We try to augment the skills rather than rely on another sensory system
For those with no residual vision skills
We substitute an alternative sensory system
Slide 17: Color Blindness: Accessible Design Techniques Do not use color alone to convey content
Use additional cues or information to convey content The flights listed below in RED have been cancelled. The flights in GREEN are departing on time.Delta 1342United 320American Airlines 787Southwest 2390 The flights listed below that have been cancelled are indicated in RED and by an asterisk. The flights in GREEN are departing on time.Delta 1342*United 320American Airlines 787Southwest 2390*
AT for Vision Augmentation : AT for Vision Augmentation Reading
Modifications to computers
Accessible to those who use enlarged screen output (screen magnification software, built-in magnification of Windows, screen magnifying lenses on monitor, CCTV)
Slide 19: Magnification Aids
Optical aids (magnifiers)
Nonoptical aids (large print books, high intensity lamps)
Eectronic aids (CCTV)
Slide 20: Low Vision: Accessible Design Techniques Limit or eliminate text within graphics
Have plenty of contrast
Slide 21: Low Vision: Simulation
Slide 22: Text presented in graphical form Real Text
AT for Vision Alternative : AT for Vision Alternative Reading
Modification to Computers
Screen reader software
Tactile – Braille technology
Automatic Reading Devices
Scanner and camera “read” the text, optical character recognition translates information into speech or braille
AT for Vision Alternative : AT for Vision Alternative Braille is widely used as tactile reading strategy
Technology provides us now with refreshable braille displays
Recorded audio material
Check out National Library Service for the Blind
Hearing : Hearing
Slide 26: Inability to hear sound
Varies depending on level of loss
Particularly important to consider in the understanding of speech
Hearing loss affects 1 out of 11 individuals
AT for Hearing AugmentationAlternatives to Hearing : AT for Hearing AugmentationAlternatives to Hearing Listening Devices
Amplification devices
Telecommunication Devices
Amplifiers, TTY
Alerting Devices
Flash, vibrate, sound
AT for Hearing AugmentationAlternatives to Hearing : AT for Hearing AugmentationAlternatives to Hearing Assistive Listening Devices (ADL’s)
FM systems
Closed-captioned television and movies
Slide 29: Deaf and Hearing Impaired Audio is unusable Video clips that include audio are unusable
Audio clips are unusable
Slide 30: Deafness: Accessible Design Techniques Provide transcripts for all audio content
Provide synchronized captions for all video content (MAGpie – free captioning tool)
Many people benefit
Students in library w/o headset
People with learning disabilities
People for whom English is not their primary language
People in a noisy environment
Everyone (content is presented in >1 medium)