You may see a icon next to your clock in the lower right. Double click it and you will see the WAV volume slider bar. Make sure that is turn all the way up.
If you don't see the speak icon, go to your control panel and then select "Sounds and audio devices". Click on the higher "advanced" button and you should see it there. Move all the sliders up.
If you don't see the WAV volume slider, just reply again and someone will go further with the instructions to get that to show.
To do a dxdiag test, just type "dxdiag" in the run command. To select the run command, click on the start button and then choose RUN.
BUT YOU MIGHT WANT TO CHECK YOUR INGAME SETTINGS FIRST!!!!!!!!
I believe it's in settings
then preferences
then voice
try to move both sliders all the way to the right. There may be 3 sliders so maybe someone can tell you what the third slider does.
Also check your sounds and make sure they are up in the game.