Side by Side Duplex Noise

[Gabriel Sastre]

Good morning, has anyone ever had any success with soundproofing between side by side duplexes. Lately both sides have been complaining more and more about noise, they both have children so fault goes both ways. But I’m curious whether it be now or during a vacancy if there’s an effective way to help soundproof a little better aside from the obvious open up all the drywall and insulate?