Download full issue (PDF 2.1MB) - Council of European ...

© Novática
Information Technologies for Visually Impaired People
order to enhance the way voice synthesis reads mathematical
formulas [46]. The Math Genie offers blind students
several ways of reading the formulas, from default reading
from left to right to an abstract way that highlights the hierarchical
structure while "folding" away the sub-expressions.
The user can navigate in the mathematical structure, moving
by way of meaningful "chunks". This is based on lexical
clues, which represent the structure of the mathematical
content.
Additional features provided by the Math Genie are:
the possibility to let the user to add so-called
"voicemarks" to expressions, that is to record audio bookmarks
attached to any sub-expression.
an online dictionary of mathematical terms accessible
during navigation in mathematical expressions through
simple keyboard shortcuts gives contextual support to the
blind users.
The current version supports English, French and Spanish
for speech, and offers facilities to add any local language
provided that a speech synthesiser is available with
the requested interface. The Braille output currently supports
the Nemeth code [26] (see Section 3.2).
7.3 Lambda
Lambda [6] is a mathematical reading and writing system
designed for blind students. The software was developed
in a project of the same name, whose meaning is in
full: "Linear Access to Mathematics for Braille Device and
Audio Synthesis". The Lambda software is mostly referred
to as the "Lambda Editor’’. It is an editor that enables a
blind student to input and to edit mathematical expressions
in a rather comfortable way.
The main characteristics of the Lambda project is that it
is built on a new code. This code is an XML code specifically
designed for supporting the Braille transcription into
8-dot pattern national codes. Each Lambda national code
has the lambda structure and a Braille character dictionary
as close as possible to the official national code.
Within Lambda, mathematical formulas may be input
in several ways:
through keyboard shortcuts.
from a structured menu.
from an alphabetic list.
from a toolbar (for sighted users mainly.).
As for output, Lambda supports these modalities:
Braille output in a special, though customisable 8
dot code.
speech synthesis - mathematical symbols are verbalised
in a descriptive language.
visual presentation in a linear code (a specific font
in which each Braille character is represented by a
visual symbol).
graphical rendering - not synchronous to input, the
graphical rendering is built when the user presses a key.
This view is then static. The graphical view is obtained
by conversion of the Lambda code to MathML.
Lambda offers several tools to support a student in editing
mathematical expressions. The most important among
these utilities is the manipulation of blocks: Every structure
with an opening and a closing tag, i.e., an expression in
parentheses, a root, a fraction, an index, or an exponent, is
considered a block. The Editor has functionality to select a
block, to enlarge or diminish the selection according to structural
levels, to delete a block, and to copy it to a different
place in the document.
As for navigation support, Lambda offers collapse and
expand functionality, which is also organised along the block
structure of a mathematical expression.
8 Future Challenges
Nowadays, the significant efforts made around the
MathML language and the progress made by rendering programs
(like Mozilla for instance) and the equation editing
software (like MathType) allow us to develop very useful
software that might help blind users to deal with the intrinsic
complexity of Mathematical Braille notations. We have
seen in this paper a few examples that provide such help
(Math Genie, Lambda).
8.1 Needs
One of the central objectives of works in this field is
now collaborative work between blind and sighted individuals,
most typically in a mainstream teaching environment,
where one blind pupil needs to be able to collaborate with
his/her sighted teacher and, perhaps, several sighted fellow
students.
This requires synchronisation of 2 representations using
2 different modalities, one dedicated for the blind and
one dedicated for the sighted. Each of these representation
must be the natural representation, that is the representation
the readers are used to. In the case of sighted people it
has to be the natural graphical view. In the case of blind
readers it has to be the official Braille notation in use in
their environment.
The synchronisation must allow each one to point a location
on the formula to show it to the other, in order to
highlight an idea or to explain an error. On the graphical
view this pointing must be done using the mouse by clicking
on the desired location. Then the specified location is
highlighted on the Braille display. On the other direction
the Braille user can click on a cursor routing key and then
make appear the selected location with a different background
on the screen.
Additionally it is necessary to be able to collapse/expand
some branches of the Maths expression in order to get
overviews of the formulas. Obviously this has to be synchronised
too.
Actually carrying out mathematical calculations is even
more difficult than reading and writing formulas. The problems
in doing formal manipulations happen because of the
complex structures that arise during a calculation: whereas
sighted people may organise a computation such that it can
be easily surveyed and navigated, blind people tend to get
UPGRADE Vol. VIII, No. 2, April 2007 39