Syag versus the Psak Halacha of the Rov of the shul both the OP and the neighbor with the raised voice (that the OP clearly stated in multiple comments that he’s unsure if anything untoward is occurring.)
Who do you choose? Syag or the Psak of the mutual Rov of both the neighbor and the OP?
I’d probably side with Syag over many “Rov of shuls”. As you are hopefully aware, being a Rav of a Shul means not much; in some places it means that you have a basic grasp of the Hebrew Alphabet (and perhaps the ability to blow a Shofar) and arrange the minyan; in some places being a Rav automatically qualifies you as a Ba’al Koreh. Not every “rov of a shul” has the knowledge, understanding or comprehension necessary to pasken shailas. Something which is in the Kitzus Shulchan Aruch? Sure. Something in the Magen Avraham? Maybe.
Something which needs a שיקול הדעת? Maybe not.
Anonymous Rabbanim are pretty worthless. I trust Posters who show (albeit anonymously) sound emotional depth, common sense and understanding of people to weigh up these situations. (Again – Everyone agrees that calling the authorities on someone who is in danger is a MUST; most agree that calling the authorities on someone who you know not to be in danger is WRONG. The question is how to classify this scenario. And if there is reasonable suspicion to think that this is even SOFEK SAKANAH, then you are obligated to report)