DESIGN GUIDELINES FOR AUDIO PRESENTATION OF GRAPHS AND TABLES

2.1. General Line Graph Sonification Guidelines Audio can be used to make visualisations accessible to blind and visually impaired people. The MultiVis Project has carried out research into suitable methods for presenting graphs and tables to blind people through the use of both speech and non-speech audio. This paper presents guidelines extracted from this research. These guidelines will enable designers to implement visualisation systems for blind and visually impaired users, and will provide a framework for researchers wishing to investigate the audio presentation of more complex visualisations. The first set of guidelines are general guidelines for the sonification of line graphs, and are applicable regardless of the number of data series present in the graph. 2.1.1. Map the y-axis of graphs to the pitch of musical notes Research has shown that the pitch of musical notes can be used to represent data by mapping values to corresponding musical notes. Mansur [6] devised a method for line graph sonification, called Sound-Graphs, in which the y-axis of a graph is mapped to pitch, and the x-axis is mapped to time such that moving along the x-axis causes a musical note, representing the corresponding y-value, to be played. The higher the y-value, the higher the pitch (Figure 1). This sonification method is used by MultiVis for line graphs and tables. 1.