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: