New opportunities for blind students : assistive tools for science learning

1. Introduction Thanks to the development of speech and tactile technologies, totally new learning opportunities opened up for visually impaired students. On the one hand screen readers and Braille displays enabled visually impaired students to actively read and write text, to exchange documents with sighted people and to use mainstream programs (e.g. for web browsing or for word processing). On the other hand, many difficulties still exist as far as scientific subjects are concerned. Scientific documents are made up of different content types, in particular: text, mathematical notation and graphical representations. Text is the written form of the spoken language and it generally does not pose problems to reading and writing through Braille or speech devices. Instead, visually impaired readers meet problems with mathematical expressions [1]. Actually, mathematical notation is represented through two-dimensional structures which are usually read by sighted readers through an overall glance at the structure and then by exploring details [2]. The overall glance allows for planning the transformations to be achieved on the expressions. Tactile and auditive perception cannot rely on this technique to understand mathematical expressions, so assistive tools are necessary to provide readers with alternative exploration and processing techniques to write, read and process mathematical expressions. Also graphical representations can be hardly accessed by visually impaired readers. They need to be represented in alternative forms in order to enable visually impaired to understand the meaning conveyed through a drawing. In particular the forms mainly used are tactile representations, verbal descriptions, which are often conveyed through speech or Braille output and a combination of audio and tactile feedback. In order to overcome the issues which are met by visually impaired students to access mathematical expressions and drawings, some assistive tools and techniques have been recently developed. They aim to facilitate blind students to go through scientific and technical studies which are highly unattended often because of the difficulties posed by mathematical notation and graphics. These tools will be described and analysed with respect to the advantages in an educational context. 2. The LAMBDA system The LAMBDA system [3], [4] is the result of the European LAMBDA project (www.lambdaproject.org). The LAMBDA system aims to facilitate reading, writing and processing of mathematical expressions through Braille device and audio-synthesis, especially taking into account the needs of visually impaired students who share their learning experience with sighted students in an educational context (e.g. in a classroom, attending a lesson, taking an exam, etc.). The core component is the mathematical editor which provides many features to compensate for the lack of sight. The mathematical expression is written in the LAMBDA editor in a linear form which is rendered by speech and on the Braille display through an 8-dots mathematical Braille code. The mathematical symbols are synchronously displayed in traditional notation on the screen so as to facilitate the sighted reader without any knowledge of Braille to understand what the blind student is writing. In order to compensate for the lack of overall glance, the expression can be browsed hierarchically. Specific operations to work on blocks which have a mathematical meaning are available. For example it is possible to select, cut and paste a fraction, the argument of a function, etc. A Python-based scripting language is available to extend the system. The system communicates with mainstream applications through converters from or to XHTML+MathML markup languages [5]. 3. Mathematics on the web: MathPlayer Up to recently, mathematical expressions have been represented on the web through images. Images cannot be read by screen readers, so mathematical resources on the web have been totally unexploited by blind people for years. Thanks to the widespread using of MathML markup language, mathematical expressions can be represented on the web through a description which can be interpreted by screen readers in order to generate the right speech output or Braille output. At present, the software MathPlayer [6] is able to interpret MathML expressions embedded in a web page and generate the corresponding speech output. Further extensions will take into account also Braille output. This tool is a step forward towards the full exploitation of scientific resources published on the web. 4. Access to computation software Symbolic and numerical computation programs are often key tools in many scientific and technical courses. The main accessibility issues concerning symbolic and numerical computation applications are related to the user interface. Generally speaking, these programs are made up of: an interpreter of a language specifically designed to express computations (e.g. "^" is often used to express powers, etc.), a kernel which performs computations, one or more front-end components which have many features to input, edit and process text and mathematical expressions, a protocol to enable client applications to communicate with the kernel. Problems rise with the user interface employed by the front-end. It often implements visually oriented interaction paradigms (e.g. the main working window is split into many boxes containing the expressions to be computed or the results of a computation, vertical or horizontal bars are used to mark a portion of text or expression as computed or to be calculated, etc.). Furthermore, the text-based language is usually rendered in traditional mathematical notation by the front-end thus making impossible reading through Braille display. Many symbolic and numerical computation programs also have a front-end with a command-line user interface. It can be used through mainstream screen readers and it is often a good alternative to the main front-end. Furthermore, the communication protocol between the kernel and a client application enables expert users to develop specialized front-end components which take into account accessibility features. The opportunities to use some symbolic and numerical programs are described in details. In particular, MATHEMATICA and SciLab programs are analysed. 5. Exploring and generating technical drawings The main techniques to explore drawings through non-visual perceptions are based on: verbal descriptions, tactile drawings and audio-tactile drawings. The most known tools to produce tactile drawings are graphical embossers [7], which can produce raised lines on paper. They prove to be extremely useful with graphical representations where text descriptions are absent or very short (e.g. in function diagrams or geometric shapes, etc.). Graphical representations which are rich of text descriptions can be successfully represented through audio-tactile representations. The tactile figure describes the structure of the image, whereas speech messages are associated to relevant spots which can be selected (e.g. by pressing on a tablet). This technique proves to be extremely useful for example with UML diagrams used in software engineering courses. The tools and techniques available are described in details with respect to drawings used in scientific courses (e.g. function diagrams, geometric shapes, automata, etc.).