Looking for Effective Accessibility of Sonificated Spatial Information to Blind People: Four Experiments

Literature about sonification technologies, that is the transformation of data relations into perceived acoustic ones, may be examined according to an objective point of view (the real capacity of acoustics to convey exactly the same information contained in a visual input), a subjective point of view (the effective capability of users with different processing capabilities to decode sonificated information), and an interactive point of view (that is the possibility of acquiring experience and improving performance through sonificated representations). According to these different perspectives three experiments were performed based on audio-tactile exploration of geo-referenced sonificated data by congenitally and acquired blind subjects that afterward were requested to recognize in a haptic modality the explored map among three distracters. In a fourth experiment a reverse paradigm was adopted, starting from the haptic exploration, and asking for recognition in the sonificated modality. The results give evidence that interactive sonification is useful for the transmission of spatial information in absence of visual information (objective perspective). New insights on how this spatial information is internally represented by means of mental maps by different categories of blind subjects were also obtained (subjective perspective). The presence/absence of previous visual experience differently influences the development of expertise in decoding sonificated spatial information (interactive perspective).