You need to find out from your neighbour exactly what the issues are; like others have suggested, going round to hear things from their side when this noise is happening, or changing something your side and awaiting further comment - or not! - from your neighbour.
One of the issues may be the construction of the properties, but also, some people are just much louder than others, and I’m not sure they realise half the time!
In our previous home (end of terrace) despite the stairs being on opposite rather than our adjoining walls, we could hear whenever anyone when thumping up and down the stairs, and that family seemed to love slamming doors! In our current home, we’re in a semi and we have a family adjoined to us who seem unable to speak at normal volume - they’ve had sound complaints from others in the road who aren’t even attached! We haven’t ever complained formally, though once had to tell them to knock it on the head when a loud weekday party ran into the early hours and I was up for work at 4:30am that morning. We also used to hear their eldest son, with the loudest booming voice, playing online with his friends. However, we never complained and just stuck on noise cancelling headphones, and now we have an eldest teenage son who plays online with his friends whose bedroom adjoins that of the eldest son next door, and we don’t tell him to quieten down; they can be on the receiving end of some normal teenager noise for a bit!!!
Generally speaking we are a much quieter household than most, and we’re sensitive to noise from others, but if that noise isn’t unreasonable then we just pop our noise cancelling headphones on until it passes. But having also lived next door in the past to someone whose frequent arguments we could hear and whose dogs barked for up to 20 hours a day - no exaggeration, we had records where we nearly got to a point of reporting to environmental health - I know how ill it can make you and how stressful it is, so I do think it’s important to establish whether your normal is most people’s too loud and if so you need to make some changes, or whether your neighbour is just more sensitive to noise and therefore it’s on them to resolve.