OP you must also consider how you are perceiving the noise that you hear. It is very clear that this issue is beyond the noise, and likely both neighbors are so sensitive to anything produced by the other, that what would have been a normal/acceptable noise level before this all started, is probably infuriating now.

Sit down and actually ask yourself f being able to hear the bass is an issue because hearing it bothers you, or because you perceive it as a sleight? I remember being bothered by a basketball being dribbled 100 yards away across the street. Sounds ridiculous, but it was 2am on a Wednesday and while I was laying there trying to sleep it was all I could hear. Each bounce sounded louder and louder in my head as I became more angry.

Same thing with my neighbors drinking outside at 11pm the other night. I love having neighbors that aren't total trash for once, but it was a Monday night and I could hear them over our fan. I went outside and confronted them. They shriveled up like cowards and pretended the guy in the next yard, shinning a spot light in their faces and asking how long they planned to be up screaming wasn't there. Now they think I am a dick. I've been meaning to go talk to them and explain I only cared because it was a week night and my kid was sleeping. I haven't gotten around to it.

Anyway, before you go running off to the police, try to consider the ACTUAL noise levels, and how it may be perceived by each side. If you leave each other alone for long enough, you'll both probably grow numb and forget why you were upset in the first place. That is unless one, or both, of you can't see the situation for what it is and continues to be a passive aggressive dickhole.

Good luck.