Hmm, it seems to me you might have the onboard microphone working in the background too, so when you type, the computer is picking these up
Go to the volume logo in the taskbar on the right and right click it, then go to Open Volume Control; or double click it alternately
If microphone is listed there, mute it , and the problem should go away.
if its not there, go to Options, Properties. There, select the Microphone to be on the list and then press Okay.
Now mute it now its there, and the problem should go away.
I hope this helps