Audio Interfaces for Improved Accessibility

According to the World Health Organization the number of people with visual impairments worldwide in 2002 was in excess of 161 million, of whom about 37 million were blind (Resnikoff et al., 2004). Although the visually impaired population is not uniformly distributed over the world, estimates for the developed countries, including the United States of America and European Union countries, go up to more than 20 million visually impaired people. Even if considering only the numbers for the developed countries, there are large numbers of population being prevented to fully access, depending on the severity of their visual impairment, today’s software applications, which are mostly based on visual interaction. The limitations to the visually impaired population caused by this reliance on visual interaction are felt both on the input and output ends of the interaction spectrum. Considering the use of visual output modalities, the limitations can range from total content inaccessibility felt by blind users, to minor limitations that are still detrimental to the user experience. These include small font sizes that make it hard to read, colour selections disregarding the problem of the colour blind population, and other presentation related issues. Input modalities are also extremely reliant on visual interaction. Although even the blind population is capable of using the traditional keyboard, pointing devices, like the mouse, are unusable by people with serious visual limitations, which hinder their perception of the pointer representation on screen. In order to improve accessibility, alternative modalities must be considered. Audio interaction is the most promising alternative to visual interaction for visually impaired users, as the recommendations toward using screen readers and voice recognition software show (W3C, 2008; Sutton, 2002). It can be used alone for users with severe visual impairments who won’t benefit from any kind of visual representation, or it can be used as a complementary or redundant modality for visual interaction, assuming greater or lesser relevance in accordance to the visual impairment level of the user population. This chapter reflects on how audio interaction can improve interface accessibility, and shows its usefulness by describing the development of an audio based interface for Digital Talking Book (DTB) listening. DTBs are primarily targeted at blind and vision impaired users, but their development under the Universal Accessibility (Stephanidis & Savidis, 2001) umbrella can extend their usage to settings where sighted users operate in constrained environments that restrict visual interaction. The chapter begins with a short summary of the issues pertaining to DTB presentation. This is relevant since a DTB player will be the application used to illustrate how audio interaction