On another system I found pulseaudio blocking speech-dispatcher when festival was used for screen reader output. Pulseaudio works for sound but spd-say part of speech-dispatcher which produces speech gets blocked by pulseaudio. I proved this by removing pulseaudio and choosing alsa as the output device in spd-conf and when I did that, speech-dispatcher and spd-say had no trouble at all working and speaking. For gnome, pulseaudio is tied into too many other applications by dependencies so if you get gnome on a system (maybe you can run it without pulseaudio included), I haven't tried installing gnome without pulseaudio yet but that'll be something else I try in a while.
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