Couple of things to check here for troubleshooting,
did you see any exclamation (warning) symbol with the Audio driver loaded in Device manager ?

If yes, the audio driver is not loaded properly.
Also, from Control Panel > Sounds > Check if you are able to view "Kinect Microphone Array" as an Audio device ? If the driver loaded properly, you will able to view the same over there.
Make sure your sensor getting enough bandwidth from USB hub (don't plug other devices which consumes bandwidth such webcam.. ) .
Also, you can try with reinstalling the SDK once.
Check this out, hope this helps !
Abhijit Blog: http://abhijitjana.net Twitter : @AbhijitJana