[10dpd]

Through the use of screen readers and braille displays.

In terms of OS's: OSX has a built in screen reader - Press Command-F5 to activate it, and follow the tutorial for more details.

Chrome has a screen reader called ChromeVox (http://www.chromevox.com)

Windows users have access to NVDA (free), JAWS (paid) or WindowEyes (paid).

EmacSpeak is available for emacs users.

However you'll find that each of these screen readers have a slightly different model that you'll have to learn.

What OS are you currently using? Being able to apply your existing mental model of how the OS works will reduce your learning time exponentially.