For example, instead of saying 'you have to listen to the person you are talking with', I want to say: 'You have to listen to your ___________'
The word is interlocutor. "You have to hear/listen to your interlocutor."
But it can refer to anyone taking part in a conversation.
"collocutor," meaning "The person with/to whom one is speaking."
collocutor noun col·loc·u·tor \kəˈläkyətə(r), kōˈ- ˈkäləˌkyütə(r)\ Definition of collocutor
: a person to or with whom one speaks
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