mm4games

There are good and bad people everywhere.  People take advantage of you, if you do not defense yourself not matter where you are - in China, Hong Kong, Canada, or in your case LA.  I am living in NYC for over 10 years, lucky I never have such problem.  

My recommendation is to know your rights, in US its governing by law and regulations.  In this case the tenant below does not have the rights to complain if the noises are consider normal behaviors and it should not affecting their normal life.  Even the police does not able to take action against either one, unless the noise is excessive.  Luckily polices that I encountered in NYC are mostly friendly from my experience.