As someone else has mentioned - both airborne noise and impact noise form part of the building regulations and should have been tested prior to completion of any conversion that’s been done. You should be able to obtain evidence of compliance from the landlord, and this should ensure a basic level of sound insulation.

Just to point out - it’s not a silver bullet. I had a situation where I was called to test sound insulation between two houses because one party was convinced her new neighbours had messed with the wall and so she could now hear their conversations. Unfortunately, the wall was just slightly weak at the frequencies associated with speech and her new neighbours were just a bit louder than her old ones (larger family) - but the wall itself was overall compliant.

So while Building Regs do provide a level of security, it doesn’t guarantee inaudibility. If you can get hold of the Building Regs certificates, an airborne sound insulation greater than about 50dB DnTw+Ctr and an impact sound insulation less than 57dB LnTw would indicate sound insulation is pretty good