For web apps you can install the tota11y [1] browser extension and use its experimental Screen Reader Wand feature to get an idea of how a screen reader will interpret elements.
tota11y uses Chrome's Accessibility Developer Tools. Deque maintains browser extensions that use their own open source engine [2]:
> For web apps you can install the tota11y [1] browser extension and use its experimental Screen Reader Wand feature to get an idea of how a screen reader will interpret elements.
An idea, perhaps, but that's all it would be rather than real-world data. Blind people don't actually use these tools.
tota11y uses Chrome's Accessibility Developer Tools. Deque maintains browser extensions that use their own open source engine [2]:
http://www.deque.com/products/axe/#aXeExtensions
Both engines could also be used in CI environments to perform a11y audits. That should help web developers target at least low hanging fruit.
[1] http://khan.github.io/tota11y/
[2] https://github.com/dequelabs/axe-core