Noise from the children is unavoidable to an extent. I had one set of tenants who would let their children ride a Big Wheels (with Real Engine Noises!) at 5 am, and another tenant who was a divorced dad and would let his kids (who were 10 and 12 and therefore definitely old enough to understand reason) run races in the building hallways between 11 and midnight. Normal kid noises are one thing, parents being overly permissive inconsiderate assholes who refuse to set reasonable limits with their children are completely different.