Just like any good element inspector helps you debug styles, accessibility inspection in the browser can help you debug HTML and ARIA exposed for assistive technologies such as screen readers. There's a similar tool in Safari (and reportedly one in Edge) but I like the Chrome one best.
As an internal Chrome experiment, this tool differs from the Accessibility Developer Tools extension in that it has privileged Accessibility API access and reports more information as a result. You can still use the audit feature in the Chrome Accessibility Developer Tools, or you could use the aXe Chrome extension. :)
To enable the accessibility inspector in Chrome stable: