Quite difficult this one.

if it was general noise i.e. the hum of an air conditioner or something like that thenit would be easy enough to isolate the particular frequencies and lower their volume.

Trying topick out and amplify one voice in a room of many (if I understand you right) will be tough indeed.

I know it's little comfort to you right now on this problem but the best way to fix audio is to get it right in the beginning. i.e. source the conversation you actually want with external microphones etc.

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