The Kinect for Windows Media Center addin has been updated to beta 4, there are lots of improvements in the new version including improved voice recognition.
I have just completed ‘Kinect for Media Center’ beta 4. Many performance improvements have been made, and most notably have done a lot of work around the Voice Recognition. I added commands to start and stop both the gestures and voice recognition should you wish to temporarily turn off that functionality. I have also implemented acoustic audio cancellation and beamforming, meaning that audio coming from Media Center should not interfere or accidently trigger voice commands.
Check out www.bradmauk.me/TheMediaCenterProject for all the details.