Sonification of Statistical Map Displays for Blind Users

Haixia Zhao, Catherine Plaisant
Department of Computer Science & Human Computer Interaction Laboratory,
University of Maryland ,
College Park , MD 20742
{haixia, plaisant}

Interactive data visualization tools are helpful to gain insight about data, find patterns and exceptions, but are usually inaccessible to vision-impaired users. In the case of geo-referenced data where users need to combine demographic, economic or other data in a geographic context for decision-making, we designed YMap, a dynamic map tool that visualizes data attributes on the map and enables slider-based dynamic queries. User studies show that YMap can help users find specific geographic regions that match a query and retrieve details, find trends and patterns or detect the correlation between attributes. As our first step to design a counterpart exploration tool for the vision-impaired, we created a virtual spatial sound display for the interactive map by synthesizing 3-D sounds of various timbres and pitches using head-related transfer function (HRTF) and tying these sounds to map regions and interface widgets. The 3-D sounds create the effect of a virtual map hung on the surface of a large virtual sphere with the user sitting in the center. The sounds have been tied to the interface in three ways: (1) gliding the cursor over the map to examine the sound of individual regions; (2) adjusting dynamic query sliders and hear the sounds of regions being filtered-out / filtered-in; and (3) using sweeping lines to scan the map and hear the sound patterns. We designed an interface using either keyboard or tablet. Our research goals are to identify effective sonification mechanisms, especially as applied to maps, and examine the effectiveness of our tool in helping vision-impaired users in large geo-referenced data set exploration. We are currently designing user experiments to investigate different sonification designs. More details about the project are available at