Yanbu. If you are just talking at a normal sound level at 2am in your own house, there is no issue. It's odd that they can hear you whilst they are upstairs in their house.
Some neighbours that live alone need to understand they will hear their neighbours as their own house is very quiet! My neighbour to my right lives alone with 2 dogs, she hangs out in her lounge at the back, we use our lounge at the front of the house mostly, which is why we can't hear her. But when I've gone in my lounge at the back, I can hear her talking, sometimes her dogs, it's quite a muffled sound. I do hear when she's hoovering and moving things around, so I can imagine she hears us and most defo my children, the tv is joined on the sharing wall, so I bet she hears that too. Her house is for sale now, so
Anytime there's been house viewings, I have turned on both tv just so the people viewing can see how much can be heard, I had no idea when we moved here and really wish I did!
My neighbour on my left, we share the stair case wall and kitchen wall, a couple in their 60s, I can hear when she moves things in her kitchen cupboard, I do always wonder how much can she hear from me.
She complained about hearing the kids run up the stairs, they usually walk, maybe a few times a week they run up to be the first to get to the bathroom. Before she complained, I had already told my kids not to run up as the neighbour will be able to hear. So anyways when she complained, I apologised and told the kids not to do so.
A week or so later, my kids drew on our drive outside and on the pavement in-front of our house with chalk, there was one small circle drawn in-front of her drive.
The next morning I got out for the morning school run, and she was waiting for me outside!!!! To tell me, to ask the kids not to draw with chalk as she has friends coming over, I laughed and said oh it's just a bit of chalk, she then responds "well I don't see you scrubbing it" wtfff, I was 8 months pregnant, couldn't believe she said that. So now I don't care about the racket my kids make on her wall side, for a woman in her 60s, has zero compassion, well your not getting any compassion from my end either then. Oh and that very day, it rained, so the chalk was washed off and no "scrubbing" needed.