Soundproofing old house with wooden floors from neighbours

Looking for some advice. We've been trying to find a sound 'consultant' but most in our area don't want to touch residential work due to how difficult it is.

Perhaps folks here would have some advice, we live in a 200+ year old house that likely shares joists with the neighbouring house. It's a protected house, meaning in the city we live in we can't make major structural changes to the house withour planning permission. When we purchased the house we sanded and stained the 200 year old pine floors and made minor changes like painting etc but otherwise left the house intact.

The house next door is split into apartments and is exempt from planning regulations. The apartments have been recently done up and all apartments are now occupied. These apartments are relatively new layouts with new floors and fittings. From a brief inspection I did when they 'went on the market', the floors are standard laminate wood floors, likely sitting on a standard thermal underlay.

Since these apartments have been occupied, we've been experiencing disruptive sound ingress. Mostly loud bangs (slamming doors, heavy foot steps, banged pots), muffled voices and noise from water pumps.

Whilst 'tolerable', the sound is non stop as the apartments are fully occupied.

I have a suspicion this noise is coming across the joists in the building and up into our house via these old floorboards and flooring brads. The boards have considerable gaps between them and the joist spans are cavernous with only wiring and plumbing running along or through them.

My thinking is we may have to lift these boards, apply soundproofing to the joists and fill these spans.

Of course, there's considerable cost in both time and money on this, so I wanted to see if this is something anyone else has experience with here and whether we're chasing the right avenue.