Under new laws in NY, anyone who considered calling 911 because they were concerned about cries for help might hesitate just as many did in 1964. The man in the dispute you are hearing could well be out tomorrow morning on no bail, and he'd be given your name as a witness within two weeks. These are new laws passed just this January to prevent long imprisonments pending trials and to aid the defense of accused criminals.
It leads to interesting dilemmas.
If you make a 911 call that a woman is being attacked, it's in your best interest that the attack proceeds and becomes serious enough that the level of violence warrants a high bail. You could make the call, realize the mistake you made, and hope he kills her just so he's not released on bail and given your name and address.