This is my theory with respect to hearing voices from downstairs. It only takes the tiniest little air gap to make a huge difference and I can tell there is one

This is my theory with respect to hearing voices from downstairs. It only takes the tiniest little air gap to make a huge difference and I can tell there is one somewhere. I'm not sure about the problem with direct contact with walls/ceilings, though. I suspect this is more down to the construction and the walls/ceiling being directly attached to the concrete shell, or something.