Your neighbors fear you.
Lots of drummers have the reputation to be violent, cranky and argumentative. Some chicks love that "bad boy" reputation.
If your home is attached, it could be vibration noise. If it's not attached, then it's pitter patter that they here.
I've never used a decible meter to find out, but you can go to your local precent and find out about what noice ordenance are aloud during what times of the day.
It's like the neighbors dog pooping on your lawn type of thing. When my neighbor's dogs bark too often, I open the window and yell "SHUT THE HELL UP ALREADY" and the barking stops. Then again I've been living here since 1959 and they all know that I'm half crazy.
The cops don't come to my home, besides I know them. I used to install car alarms for them.