An Open Vis Conf video:
Doug Schepers (on the SVG working group for the W3C) discusses making visualizations accessible for users with a screen reader.
Talk description from http://openvisconf.com/#schedule :
"Data visualization is an efficient way of conveying information, but sometimes accessibility may suffer. This talk will cover well-known challenges and pitfalls for accessible information graphics, and describe techniques to overcome them. I will focus on Web solutions using SVG, HTML, ARIA, and the Web Audio API. I will also describe some of the new accessibility features in the upcoming SVG2 specification, including the SVG Connectors module, which will allow authors to easily build interactive SVG node-line graphs."
The other conference videos are also up: https://www.youtube.com/user/BocoupLLC