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Tactile perception and the information processing basis of tactile speech prostheses for the deaf


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Mahar, Douglas P 1990 , 'Tactile perception and the information processing basis of tactile speech prostheses for the deaf', PhD thesis, University of Tasmania.

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The research reported in this thesis took as its
starting point the question of whether touch has the
information processing characteristics required to deal with
speech transforms. A review of the current status of tactile
speech prostheses and of the range of potential limitations to
touch's ability to deal with speech transforms, lead to the
identification of two specific research foci.
First, it was argued that an appropriate strategy for
tactile aid development is to establish where tactile and
auditory processes overlap and where they differ, then to take
advantage of any similarities, or compensate for any
differences, between these modalities in the design of the
prosthesis. In line with this argument, a series of experiments
was undertaken to test previous suggestions that there is an
underlying similarity between auditory and tactile
representations of stimuli. In support of these claims, it was
found that auditory and tactile versions of patterns are
easier to compare than are auditory and visual versions of
those patterns. Subsequent research revealed that one aspect of
this processing affinity between touch and hearing is that both
modalities, unlike vision, process temporally distributed
information more efficiently than spatially distributed
information. This finding has broader theoretical significance
in view of the current controversy regarding the division of
senses according to a spatial vs temporal criterion.
The second research focus addressed was whether touch has the spatial and temporal acuity required to deal with
speech transforms. It was argued that the limiting factors in
tactile spatial and temporal acuity were more likely to occur
at the higher level of touch's ability to deal with the strong
interactive effects between pattern elements, rather than at
the lower level of two-point thresholds in time and space. As
masking is a primary interactive force between tactile pattern
elements, an attempt was made to resolve the ongoing debate
regarding the extent to which tactile masking effects either
limit the perception of complex tactile patterns by obscuring
the identity of pattern elements or facilitate this task via a
process of perceptual integration.
This question was investigated by measuring the
discriminability of three-element tactile patterns as the
spatial and temporal separation, and hence the level of
masking, between pattern elements was varied. It was expected
that performance would De best at closer element spacings, due
to the greater opportunity for perceptual integration to occur.
Contrary to this prediction, it was found that the increasing
levels of masking induced by decreasing the spatial and
temporal separation between pattern elements caused a decrease
in the discriminability of the patterns.
One caveat to the acceptance of this result was the
possibility that training may be required before touch can take
advantage of any beneficial interactions between pattern
elements, a possibility supported by the anecdotal reports of
the subjects. Tentative support for this suggestion was provided by a pattern learning experiment involving three
subjects from the previous experiment. After brief experience
with closely spaced tactile patterns, the subjects were able to
discriminate these stimuli at least as well as widely spaced
tactile patterns.
While failing to demonstrate the proposed beneficial
effects of integration, these results did indicate that close
spatial and temporal proximity between tactile pattern elements
may not adversely affect the discriminability of those
patterns. If subsequent research confirms this tentative
finding, then the implication for tactile speech prostheses is
that the display employed need not avoid the strong masking
effects induced by close spatial and temporal proximity between
speech pattern elements.
In summary, this thesis showed that there is a general
similarity between auditory and tactile perceptual
representations of patterns which may both assist in the
implementation of tactile speech prostheses, and advantage
touch over vision for this purpose. Second, it appears that
although tactile pattern perception is initially impeded by the
occurrence of masking effects between pattern elements, this
performance deficit may be removed once the observers have
sufficient experience with the stimuli. There is, however, a
clear need for further research before this tentative
conclusion can be confirmed.

Item Type: Thesis - PhD
Authors/Creators:Mahar, Douglas P
Keywords: Deaf, Touch, Speech perception, Auditory perception
Copyright Holders: The Author
Copyright Information:

Copyright 1990 the Author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (Ph.D.)--University of Tasmania, 1991. Includes bibliographical references (leaves 194-207)

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