How to amplify background audio? (Or any lip readers here?)

On OS X.

I’d like to amplify the background audio of a video I have. The audio is most prominently a stage presenter speaking with two people having a normal conversation in the background (on camera, right behind the stage), but it’s difficult to hear parts of their talk. I have changed the contrast to read their lips a little better, but I’m still having trouble.

Ideally, I’d like to isolate that background conversation, or at least reduce the main audio as much as possible. Can anyone help me?

I’ve been playing around with the equalizer in VLC, but I have Audacity and would like to know whether there are any editing tips/tricks. That said, I have no experience with A/V editing.

If anyone has suggestions or would be willing to take a took at the video and sound (especially if you’re good at lip reading), please let me know! Thank you!

Audacity has an Equalization effect which is probably a bit more powerful than the one in VLC: but I don’t think that it is likely to help much. As a rule of thumb, if you can’t hear what the person is saying due to other sounds covering it up, then you will not be able to recover the voice without specialist equipment. If this is required for a legal case you should consult an audio forensic expert. We do not provide an audio forensic service.
audio forensics - Google Search.