The voice is for RR to 'speak' the commands not to be able to control RR via voice.
for voice control there are two plugins.
RRVoice is an older plugin that only works on XP and is primarily designed to work with the DFX skn.
DFXVoice is the new plugin and is designed on Win7, but should work on XP, to work with any skin but is still really in beta stage.
Yes I know it is ironic that the one named DFXVoice is the universal one and the RR one is more DFX specific. And it has been pointed out before.