This article mentions some details about Orca (GNOME-ORCA) in Debian. Orca is the graphical screen reader for the GNOME environment.
If you have enabled accessibility during the Debian installation and also installed a desktop system, accessibility is enabled by default and you only have to install Orca. This only works for GNOME, Mate, Cinnamon and Unity at the moment, but can be activated manually. See the section on autostarting Orca.
Installation and configuration on a usual Debian system
If you installed Debian without accessibility features, you should do the following steps:
sudo aptitude install gnome-orca
In a graphical session, open a terminal or press Alt+F2 and type orca -s to start the setup. If you are unable to do so, it is best to enable the autostart of Orca and run the setup with Orca support with the command orca -r -s.
- In the dialog(s), you can select the options you like, including Orca modifier, etc. After this procedure, Orca should start automatically.
Orca does not offer magnification itself, however a variety of solutions exist, which are documented ?here
Orca has support for two rendering engines, Gecko and ?WebKit. The former is used within firefox and has the best support. There are several ?WebKit browsers and they work to a certain degree, but cannot be considered production-ready with Orca yet. You need to press F7 in those browsers to activate caret browsing.
Alternatively, there are several text-mode browsers for the console available too, but they are obviously less convenient.
Other speech synthesizers
Newer, experimental versions of Orca
If you don't want to compile Orca from source but still try a newer version (at your own risk), you can try using the version from unstable (or if available, from experimental). For this, you have to configure apt-pinning. Add a Debian unstable / experimental-source of Debian, update your package lists and run
sudo aptitude -t unstable install gnome-orca
WARNING: unstable and experimental aren't have their names without reason!
NOTE: It is possible, that after this the gdm greeter is not any longer able to start Orca at the login screen.