Either:
1) Don't watch your own stream while you're streaming.
2) Set your webcam's audio device to DISABLE; if it's set to your mic it's being capped twice, once through the Mic channel in settings, and once with the webcam.
Past that, post a logfile from a live session at least 5 minutes in length, as it requests when you open a new thread in Q&H. We really do need it to see what's going on, to be able to help.