Apologies in advance. Haven't done much video editing, but have been able to find answers to all of my questions so far on You tube. This one I haven't been able to figure out, but I'm guessing there's a relatively simple answer. Sorry if I don't use the correct terminilogy in any cases. 

I am working on a new project. I have added two overlapping video tracks. I will be switching back and forth between the two tracks, which I do know how to do. However, the audio for both video tracks appears in a single audio track. I know how to change the volume overall, but I want to use the audio from one video track and have the other video track's audio completely silent (regardless of which video track is being used). The second video source has some good video that I want to use intermittently, but was shot from a location that resulted in nothing but wind noise in the audio. So I don't want to hear this audio at all, at no points in time. I've tried inserting a volume envelope, but as far as I can tell that just results in changing the volume for both tracks. Is there a way for me to "split" the audio into two separate tracks so that I can edit the volume of each individually? Or any other options to accomplish what I'm trying to do?

Thank you!

Scott