LG enV VX-9900

When you go to the main menu, setings & tools, sound seetings voice commands, what does the voice commands volume raise the volume for? Is it the vole level for when you hit the space bar for the voice commands and say the name of the person you're calling? Is it when you have the ringer and ID on so when someone texts or call you, your phone says call from or message from? I'm confused. Thanks for the help.