Orca (assistive technology)

Orca is an open -source screen reader for the GNOME desktop environment. He is in most GNU / Linux distributions such as openSUSE, Ubuntu, Fedora, but also included under opensolaris. Although Orca is not the first screen reader for the graphical interface using Linux, it has established itself as the only and has been published since 2005 with each release of GNOME.

Orca works with the Braille display control program BrlTTY be able to address serial, USB and Bluetooth braille displays can. Orca gets its data from the Assistive Technology Service Provider Interface (AT- SPI). It interacts, in principle, with all the applications that make their surface via AT- SPI accessible such as Adobe Reader, Eclipse, Mozilla Thunderbird or OpenOffice.org. The current stable version of Orca always depends on the current GNOME version.

The name of Orca refers to the popular proprietary competitor JAWS: Jaws is the original title of the movie Jaws; there is Orca the name of the boat is done with the hunt for the shark, named after the only natural enemy of the white shark, the great whale. Other major screen readers and their manufacturers are similarly named after sea creatures like pinball or Dolphin.


The first version of Orca was officially launched in November 2005. Prior to Sun Microsystems had decided to expand its involvement in the GNOME project and to develop a free screen reader for GNOME. Marc Mulcahy, a blind programmers at Sun, developed the first working prototype. In January 2010, Sun Microsystems was acquired by Oracle. As part of the company's internal restructuring and the development of Orca has been set. Open letters from the community were not answered by Oracle. Orca eventually became a joint project, which is managed, developed and translated by volunteers.

Functionality and operation


Orca uses by default a free speech issue, eSpeak. Speech outputs are controlled under Orca with language modules, so-called backends.

Orca uses to control for voice outputs three different modules:

  • Emacspeak
  • Gnome Speech (deprecated)
  • Speech Dispatcher

You can also use with Orca paid synthesizer, such as IBM ViaVoice. Such external voice outputs are then mostly driven by the Speech Dispatcher.


Orca can be controlled via the screen reader BrlTTY. This BrlTTY acts as a control program for braille displays, that is, it represents the driver. Is controlled BrlTTY of Orca on the brlapi, a control protocol for BrlTTY.

Orca are the contents of the screen on the Braille display with context. Thus one finds in the menu bar next to the word "File" and "menu" or " mnu " (depending on verbosity ). This allows a better view of the screen. Furthermore, Orca text also display in shorthand and also send spoken messages on the braille display in newer versions.


Orca can also provide a screen magnifier for visually impaired greatly. There the user can the degree of magnification, contrast, color settings and set some more. To accomplish this, a computer with more than 512 MB ​​of RAM be available, as this could lead to stuttering of the image otherwise.