raising volume

I need to use a filter to raise the other end of a phone call but not the other people. Could I even drop out the other voices and raise just the faint one? Thank you for any advice

How long is the conversation?

If it is not to long, and for the best results, do it manually.

Use the envelope tool to lower the loud passages to the same level as the quiet ones.
Mix and render the result.
Apply the Amplify or Normalize effect to bring the entire conversation back to normal level.

– Bill