How do I get my landlord to fix the squeaky floors above me?

My new apartment is on the 1st floor, so I can hear footsteps, conversations, and annoying squeaky floors from above. It is so loud that it wakes me up at night, and I have to raise my voice when I'm talking to someone who's right next to me. I asked my landlady to repair the squeaky floors but she says she cannot do anything about it. Should I just go ahead and hire a contractor anyway and have her reimburse me later? What if she refuses? I would also have to gain the cooperation of the neighbors above to let me tear apart their flooring. Any ideas about how I should go about handling this?