I had the same problem for a few days one time dave..it is very irritating..you need to go into windows default..the small gray speaker in task bar,and right click,adjust audio properties,then test voice I believe it says..you will have to adjust some settings..what you are getting is feed-back,and something,I forget what,will need to be changed..keep using the properties to test what you are doing and listen to your voice..The first time you do it with your current problem the REVERB will be INTENSE and IRRITATING...
I am assuming you have Onboard sound..REALTEK HD????
ANd BTW I am currently having a very odd problem for those interested..
I push T or f12 and talk,,but when I let off,the game MOMENTARILY FREEZES,recently started this,and very irritating as well..Any ideas???
Falcon