Firstly, I don't think that voice activation is enabled by default on most machines, so try using the keyboard and mouse to enter commands rather than shouting at the computer.
Secondly, you haven't told us what game it is. Find out and while you're at it, tell us what OS you are using. Then post both bits of information here or, better yet, search Google yourself to see if anyone else is having this problem
Have a nice day.