Can you recognise the people talking as talk or is it just a noise in the background like mumbling? If it is just 'mumbling' then it is a low frequency noise as opposed to a mid or high frequency noise and may be able to be reduced using audio filters. The downside is it will probably affect your granddaughters audio aswell as they are all interwoven on the one track. In future try and put a tie clip microphone on the person who is talking or singing to isolate them as much as possible from the background noise. If this was a television or film production your daughter would go back into a recording studio and she would record her voice singing again, it's known as ADR... fancy trying something similar yourself?

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