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Development and Evaluation of Two Prototypes for Providing Weather Map Data to Blind Users Through Sonification

Jonathan Lazar, Suranjan Chakraborty, Dustin Carroll, Robert Weir, Bryan Sizemore, and Haley Henderson

Journal of Usability Studies, Volume 8, Issue 4, August 2013, pp. 93 - 110

Article Contents


Introduction

In recent years there have been significant advances in developing websites that are accessible for individuals with disabilities. The Web Content Accessibility Guidelines (WCAG) from the Web Accessibility Initiative (http://www.w3.org/wai) provide clear standards for labeling visual images: providing equivalents for mouseovers, labeling forms and tables, and providing accessible equivalents for video and audio. Many countries have legal guidelines related to web accessibility, and most national government guidelines tend to be based on the WCAG (Meiselwitz, Wentz, & Lazar, 2010). However, one of the more challenging aspects of accessible web design is coming up with accessible equivalents of data visualizations that can be effectively used by blind users. Data visualizations are typically used to improve comprehension of large quantities of data as vision allows for the perception of large quantities of spatial information quickly (Fritz & Barner, 1999). A central challenge in web accessibility is devising alternative modes of representing such visual data, which frequently does not easily translate into textual equivalents, on web pages for blind users. While an important topic, there have not been many research projects performed about the accessibility of data visualizations.

It is important to note that users’ terminology differs depending on their country and professional training. In the context of this work, the term “blind users” has different meanings. For instance, in the US, “blind users” often refers to anyone with any type of visual loss; whereas in the UK, “visually impaired” is often used to describe people with low vision, while “blind” is used to describe someone with no useful residual vision. In this paper, the term “blind” refers to people with no residual vision; they rely strictly on tactile materials and sounds (typical non-visual approaches), not vision.

Accessibility researchers have proposed that equivalencies may be accomplished through a multimodal approach such as haptic visualization, force feedback, and/or sonification (Fritz &Barner, 1999; Su, Rosenzweig, Goel, de Lara, & Truong, 2010). Haptic visualizations use the sense of touch by applying forces, vibration, or motion to a user. Force feedback is a particular form of such haptic feedback. A typical example would be vibrating cell phones when ringing or touchscreens responding with vibrations when a user performs particular actions. Sonifications, on the other hand, rely on sound based feedback to user actions.

One of the co-authors of this paper (Lazar) had previously worked on a sonification project, and based on that project, a local Maryland resident, who is blind, contacted our team about working on developing better access to weather maps for blind users. This study describes our response to that request: requirements gathering, usability evaluation, and iterative design of sonification for blind users to understand weather map data.

Maps represent a very common visualization approach on webpages. Figure 1 (adapted from www.recovery.gov) shows a typical example of a data visualization that is based on a map. A quick visual map sweep of Figure 1 allows users to see that the states marked with darker colors have a higher percentage of residents under the age of 18, and those states tend to be clustered in the southwest part of the United States. Equivalents of visualizations for blind users tend to provide a table of data presented on the map (Plaisant, 2004), which while technically equivalent, does not allow for quick map sweeps to obtain an overview of data that is the key first step of usage of information visualizations.

Figure 1

Figure1. Map-based visualization of population data (darker states have more residents under 18)

Previous research has addressed this problem through the development of sonified maps that used non-textual audio output to allow users to comprehend detailed as well as trend data rendered within maps(Zhao, Shneiderman, Plaisant, & Lazar, 2008; Zhao, Smith, Norman, Plaisant, & Shneiderman, 2005). In this study, we build on existing research to investigate the use of sonification to represent weather map data for blind users. The specific goals for this study were to (a) perform a requirements gathering to learn more about how blind users seek information about weather, (b) modify an existing sonification application that was designed for population statistics to provide live feeds of weather data in a sonified format, and (c) evaluate the new application with a sample of blind users.

The rest of the article is organized as follows. First we describe additional research and applications related to sonified maps. Next we describe our methodological approach in requirements gathering, and developing and evaluating a sonified solution for providing accessible map-based data for blind users. Finally we discuss the implications and future development and research directions.

 

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