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ACCESSIBLE Deliverable D5.5b
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Grant Agreement No. 224145
the spectrum. They have a neutral point at a greenish wavelength around 492nm that
is, they cannot discriminate light of this wavelength from white.
Deuteranopia: Lacking the medium - wavelength cones, those affected are again
unable to distinguish between colours in the green yellow red section of the spectrum.
Their neutral point is at a slightly longer wave-length, 498nm.
Tritanopia: Lacking the short - wave-length cones, those affected are unable to
distinguish colors along the blue yellow dimension.
Night Blindness (Nyctalopia) is a condition making it difficult or impossible to see in
relatively low light. It is a symptom of several eye diseases. It can be described
as insufficient adaptation to darkness.
Extreme Light Sensitivity (Photophobia) is a symptom of abnormal intolerance to
visual perception of light.
Retinitis pigmentosa (RP) is a group of genetic eye conditions that leads to incurable
blindness. In the progression of symptoms for RP, night blindness generally precedes
tunnel vision by years or even decades.
Parkinson’s disease is a degenerative disorder of the central nervous system. Early in
the course of the disease, the most obvious symptoms are movement - related; these
include shaking, rigidity, slowness of movement and difficulty with walking and gait.
Dyslexia is a very broad term defining a learning disability that impairs a person’s
fluency or comprehension accuracy in being able to read, and which can manifest
itself as a difficulty with phonological awareness, phonological decoding,
orthographic coding, auditory short-term memory, or rapid naming.
Conductive hearing loss occurs when there is a problem conducting sound waves
anywhere along the route through the outer ear, tympanic membrane (eardrum), or
middle ear (ossicles). It may occur in conjunction with sensorineural hearing loss or
alone. It is caused by any condition or disease that impedes the conveyance
of sound in its mechanical form through the middle ear cavity to the inner ear. A
conductive hearing loss can be the result of a blockage in the external ear canal or can
be caused by any disorder that unfavourably effects the middle ear’s ability to
transmit the mechanical energy to the stapes footplate. This results in the reduction of
one of the physical attributes of sound called intensity (loudness), so the energy
reaching the inner ear is lower or less intense than that in the original stimulus. Thus,
a reduction in sound level, or the ability to hear faint sounds is encountered.
Sensorineural hearing loss (SNHL) is a type of hearing loss, in which the root cause
lies in the vestibulocochlear nerve, the inner ear, or central processing centers of the
brain. It thus results from inner ear or auditory nerve dysfunction. The sensory
component may result from damage to the organ of Corti, or an inability of the hair
cells to stimulate the nerves of hearing, or a metabolic problem in the fluids of the
inner ear. The neural or retrocochlear component can be the result of severe damage
to the organ of Corti that causes the nerves of hearing to degenerate, or it can be stem
from inability of the hearing nerves themselves to convey neurochemical information,
through the central auditory pathways. Like conductive hearing loss, it reduces the
intensity of sound, but it can also lead to distortion of the perceived sound.
The common symptoms of the above impairments, as reported in the relevant
literature (several indicative of which are presented in Table 6), formed the basis
towards the development of filters that would simulate their impact during HCI. The
development of these filters consisted of two phases. The first phase involved the
initial implementation of visual, motoric, hearing and cognitive filters, on the basis of
parameters, such as the ones presented in Table 6. These initial filters were evaluated
(Final Draft)
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