Hi I am spanish, so sorry for my bad english...😉
Ok... I will explain you my situation... i am blind, and I have installed debian using the onboot install with speak synthesis option. Doing that, when the installation success, i am not able to use any screen reader on graphical interface, but Espeakup and brltty are not affected by this. I mean, I can use the text mode only option, but when i try to use mate or some other graphical interfaces the screen reader is not able to use the sound output. In general terms, the graphical interface has no sound output, because when I level up the volume there is no sound. But, in text mode it works properly. I have been researching, and I think that the problem could be the sound dispatcher server, because when I uninstall the Espeakup and speechd-up pacakges it works againt in graphical interface. But it's not a good solution for me, because I use to use the textmode only, but i want to have the graphical interface too. Thanks and I am waiting your answer
