On the evaluation of novel sonification techniques for non-visual shape exploration

There are several situations in which a person with visual impairment or blindness needs to extract information from an image. For example, graphical representations are often used in education, in particular, in STEM (science, technology, engineering, and mathematics) subjects. In this contribution, we propose a set of six sonification techniques to support individuals with visual impairment or blindness in recognizing shapes on touchscreen devices. These techniques are compared among themselves and with two other sonification techniques already proposed in the literature. Using Invisible Puzzle, a mobile application which allows one to conduct non-supervised evaluation sessions, we conducted tests with 49 subjects with visual impairment and blindness, and 178 sighted subjects. All subjects involved in the process successfully completed the evaluation session, showing a high level of engagement, demonstrating, therefore, the effectiveness of the evaluation procedure. Results give interesting insights into the differences among the sonification techniques and, most importantly, show that after a short training, subjects are able to successfully identify several different shapes.