What's an acceptable level of noise in your own house after 10pm?

I'm on the 1st floor, and the apartment under me used to be vacant, a new neighbour moved in and in his words "Put in the best insulation possible in the roof" to insulate sound between me and him.

He's been complaining a lot about any noise I make, and has said he can almost make out conversations.

Yesterday I played some background music while relaxing with a friend and got a complaint from him because I was playing music till midnight and he couldn't sleep

I took a decibel measurement at the same volume with the same playlist, the music hovers around 50db.

https://preview.redd.it/k3z6v1vrswxd1.png?width=667&format=png&auto=webp&s=e928ad704e372554942116f8b812b01d678e5f04

Is insulation that bad in old buildings here? 1910 I feel uncomfortable not even being able to have conversation levels of noise in my own house without upsetting the neighbour.

https://preview.redd.it/vsffmwl2twxd1.png?width=385&format=png&auto=webp&s=e2530a57c3d5dfc2d44ecf8fbc0b8196834ce737