Track level gain too low

Hi Folks,

I've been creating a movie and all was going splendidly until suddenly, while recording voiceover, the input (gain level?) of my recordings dropped drastically.  I know I must have adjusted something incorrectly but I have no idea what it was.  You can see the problem in the image below.  The left audio track is what I used to get, the one on the right is what I get now.  I know I can adjust the track volume after the recording, but it adds too much noise unless I edit each clip in Audition (a painfully slow process).    Any ideas from the experienced users out there?

By the way.  I'm using a Microsoft surface with the default Realtek microphone array.

Thanks in advance!