Chapter 11. Configuring a System for Accessibility Accessibility in Red Hat Enterprise Linux 7 is ensured by the Orca screen reader, which is included in the default installation of the operating system. This chapter explains how a system administrator can configure a system to support users with a visual impairment. Orca reads information from the screen and communicates it to the user using: a speech synthesizer, which provides a speech output a braille display, which provides a tactile output For more information on Orca settings, see its help page . In order that Orca 's communication outputs function properly, the system administrator needs to: configure the brltty service, as described in Section 11.1, "Configuring the brltty Service" switch on the Always Show Universal Access Menu , as described in Section 11.2, "Switch On Always Show Universal Access Menu " enable the Festival speech synthesizer, as described in Section 11.3, "Enabling the Festival Speech Synthesis System " 11.1. Configuring the brltty Service The Braille display uses the brltty service to provide tactile output for visually impaired users. Enable the brltty Service The braille display cannot work unless brltty is running. By default, brltty is disabled. Enable brltty to be started on boot: Authorize Users to Use the Braille Display To set the users who are authorized to use the braille display, choose one of the following procedures, which have an equal effect. The procedure using the /etc/brltty.conf file is suitable even for the file systems where users or groups cannot be assigned to a file. The procedure using the /etc/brlapi.key file is suitable only for the file systems where users or groups can be assigned to a file. Setting Access to Braille Display by Using /etc/brltty.conf Open the /etc/brltty.conf file, and find the section called Application Programming Interface Parameters . Specify the users. To specify one or more individual users, list the users on the following line: To specify a user group, enter its name on the following line: Setting Access to Braille Display by Using /etc/brlapi.key Create the /etc/brlapi.key file. Change ownership of the /etc/brlapi.key to particular user or group. To specify an individual user: To specify a group: Adjust the content of /etc/brltty.conf to include this: Set the Braille Driver The braille-driver directive in /etc/brltty.conf specifies a two-letter driver identification code of the driver for the braille display. Setting the Braille Driver Decide whether you want to use the autodetection for finding the appropriate braille driver. If you want to use autodetection, leave braille driver specified to auto , which is the default option. Warning Autodetection tries all drivers. Therefore, it might take a long time or even fail. For this reason, setting up a particular braille driver is recommended. If you do not want to use the autodetection, specify the identification code of the required braille driver in the braille-driver directive. Choose the identification code of required braille driver from the list provided in /etc/brltty.conf , for example: You can also set multiple drivers, separated by commas, and autodetection is then performed among them. Set the Braille Device The braille-device directive in /etc/brltty.conf specifies the device to which the braille display is connected. The following device types are supported (see Table 11.1, "Braille Device Types and the Corresponding Syntax" ): Table 11.1. Braille Device Types and the Corresponding Syntax Braille Device Type Syntax of the Type serial device serial:path [a] USB device [serial-number] [b] Bluetooth device bluetooth:address [a] Relative paths are at /dev . [b] The brackets here indicate optionality. Examples of settings for particular devices: You can also set multiple devices, separated by commas, and each of them will be probed in turn. Warning If the device is connected by a serial-to-USB adapter, setting braille-device to usb: does not work. In this case, identify the virtual serial device that the kernel has created for the adapter. The virtual serial device can look like this: Set Specific Parameters for Particular Braille Displays If you need to set specific parameters for particular braille displays, use the braille-parameters directive in /etc/brltty.conf . The braille-parameters directive passes non-generic parameters through to the braille driver. Choose the required parameters from the list in /etc/brltty.conf . Set the Text Table The text-table directive in /etc/brltty.conf specifies which text table is used to encode the symbols. Relative paths to text tables are in the /etc/brltty/Text/ directory. Setting the Text Table Decide whether you want to use the autoselection for finding the appropriate text table. If you want to use the autoselection, leave text-table specified to auto , which is the default option. This ensures that local-based autoselection with fallback to en-nabcc is performed. If you do not want to use the autoselection, choose the required text-table from the list in /etc/brltty.conf . For example, to use the text table for American English: Set the Contraction Table The contraction-table directive in /etc/brltty.conf specifies which table is used to encode the abbreviations. Relative paths to particular contraction tables are in the /etc/brltty/Contraction/ directory. Choose the required contraction-table from the list in /etc/brltty.conf . For example, to use the contraction table for American English, grade 2: Warning If not specified, no contraction table is used. 11.2. Switch On Always Show Universal Access Menu To switch on the Orca screen reader, press the Super + Alt + S key combination. As a result, the Universal Access Menu icon is displayed on the top bar. Warning The icon disappears in case that the user switches off all of the provided options from the Universal Access Menu. Missing icon can cause difficulties to users with a visual impairment. System administrators can prevent the inaccessibility of the icon by switching on the Always Show Universal Access Menu . When the Always Show Universal Access Menu is switched on, the icon is displayed on the top bar even in the situation when all options from this menu are switched off. Switching On Always Show Universal Access Menu Open the Gnome settings menu, and click Universal Access . Switch on Always Show Universal Access Menu . Optional: Verify that the Universal Access Menu icon is displayed on the top bar even if all options from this menu are switched off. 11.3. Enabling the Festival Speech Synthesis System By default, Orca uses the eSpeak speech synthesizer, but it also supports the Festival Speech Synthesis System . Both eSpeak and Festival Speech Synthesis System (Festival) synthesize voice differently. Some users might prefer Festival to the default eSpeak synthesizer. To enable Festival, follow these steps: Installing Festival and Making it Running on Boot Install Festival: Make Festival running on boot: Create a new systemd unit file: Create a file in the /etc/systemd/system/ directory and make it executable. Ensure that the script in the /usr/bin/festival_server file is used to run Festival. Add the following content to the /etc/systemd/system/festival.service file: Notify systemd that a new festival.service file exists: Enable festival.service : Choose a Voice for Festival Festival provides multiples voices. To make a voice available, install the relevant package from the following list: festvox-awb-arctic-hts festvox-bdl-arctic-hts festvox-clb-arctic-hts festvox-kal-diphone festvox-ked-diphone festvox-rms-arctic-hts festvox-slt-arctic-hts hispavoces-pal-diphone hispavoces-sfl-diphone To see detailed information about a particular voice: To make the required voice available, install the package with this voice and then reboot:

Commands:
~]# systemctl enable brltty.service
api-parameters Auth=user: user_1, user_2, ... # Allow some local user
api-parameters Auth=group: group # Allow some local group
~]# mcookie > /etc/brlapi.key
~]# chown user_1 /etc/brlapi.key
~]# chown group_1 /etc/brlapi.key
api-parameters Auth=keyfile: /etc/brlapi.key
braille-driver auto # autodetect
braille-driver xw # XWindow
braille-device serial:ttyS0 # First serial device braille-device usb: # First USB device matching braille driver braille-device usb:nnnnn # Specific USB device by serial number braille-device bluetooth:xx:xx:xx:xx:xx:xx # Specific Bluetooth device by address
serial:ttyUSB0
You can find the actual device name in the kernel messages on the device plug with the following command:
~]# dmesg | fgrep ttyUSB0
text-table auto # locale-based autoselection
text-table en_US # English (United States)
contraction-table en-us-g2 # English (US, grade 2)
~]# yum install festival festival-freebsoft-utils
~]# touch /etc/systemd/system/festival.service ~]# chmod 664 /etc/systemd/system/festival.service
[Unit] Description=Festival speech synthesis server [Service] ExecStart=/usr/bin/festival_server Type=simple
~]# systemctl daemon-reload ~]# systemctl start festival.service
~]# systemctl enable festival.service
~]# yum info package_name
~]# yum install package_name ~]# reboot