"If you are listening to the page (via screen reader software), a lot of information can prevent you from finding what you are looking for," says T.V. Raman, who works for Google Accessible Search.
The new service is also useful for webmasters to test how accessible are their sites. As you can see, google.com is not accessible enough to rank high when searching for "Google" (see the screenshot) - google.com is ranked #73. That means, the results are more accessible, but also less relevant. At least, for now.