  Diagrams often appear as node-link representations in many contexts, such as
taxonomies, mind maps and networks in textbooks. Despite their pervasiveness,
they present significant accessibility challenges for blind and low-vision
people. To address this challenge, we introduce Touch-and-Audio-based Diagram
Access (TADA), a tablet-based interactive system that makes diagram exploration
accessible through musical tones and speech. We designed and developed TADA
informed by insights gained from an interview study with 15 participants who
shared their challenges and strategies for accessing diagrams. TADA enables
people to access a diagram by: i) engaging in open-ended touch-based
explorations, ii) allowing searching of specific nodes, iii) navigating from
one node to another and iv) filtering information. We evaluated TADA with 25
participants and found that it can be a useful tool for gaining different
perspectives about the diagram and participants could complete several
diagram-related tasks.
