Biomedical Engineering Reference
In-Depth Information
FIGURE 7-20
New generation of
the vOICe camera
mounted in a
glasses frame.
(Meijer 2006)
in her head as “ghostly” but real. At a meeting of the Cognitive Neuroscience Society in
New York, researchers from Harvard Medical School announced that when they viewed
the activity in the brains of two vOICe users (one blind at birth, the other who went blind
later in life), it was in many respects like that of a sighted person while seeing. However,
in tests undertaken by Alex Storer (2006), though his subjects' identification capabilities
improved using vOICe for long periods none felt that the experience was visual in nature.
For obvious reasons, not everyone has the inclination to walk around with a
head-mounted camera and a laptop, so Meijer has modified his setup to work using a
camera phone. Now, after downloading a simplified version of the software (http://www
.seeingwithsound.com), practically anyone can point her camera phone at what she wants
to see and have a listen to what it looks like.
An alternative for more serious users includes a netbook processor, stereo ear buds,
and the installation of the camera into the bridge of a pair of fashion sunglasses shown in
Figure 7-20.
So far, the research community has not yet found conclusive answers with respect
to the potential of this approach for the blind, and the relevant limitations in human
auditory perception and learning abilities for comprehension and development of visual
interpretation remain largely anecdotal. In addition, the training effort is expected to be
significant while involving perceptual recalibration for accurate sensorimotor feedback.
The U.S. National Science Foundation is now funding the first controlled study to look
at the benefits of the system while simultaneously attempting to find an optimal training
protocol (Trivedi, 2010).
One of the key research questions is to what extent the use of a sensory substitution
system can not only provide synthetic vision in a functional sense for extended situational
awareness through active sensing but also lead to visual sensations through forms of
induced artificial synesthasia.
Other researchers including Stefan Strahl of the UCL Ear Institute in London and
Lucy Irving of the University of Brighton have been examining similar aspects of sensory
substitution using the vOICe system, with most of their results available on the Web.
The latest functional magnetic resonance imaging (fMRI) results show that in novice
users the auditory cortex is involved in the interpretation of the soundscape but, after
10-15 hours of training, activity in the visual cortex and an area known as the occipital
tactile-visual (LOtv) region increases. Recent experiments on advanced users including
Fletcher involved the use of repetitive transcranial magnetic stimulation (rTMS) to close
down the LOtv region. When this occurred they lost the ability to “see” and became
confused and frightened (Trivedi, 2010).
