That explains the transmission of impact sound and the like, but not overhearing conversations. Either the original poster has exceptionally sharp ears or the partition wall simply isn't very soundproof (aerated concrete, unfilled Poroton?). But as I already mentioned in my first post, there will be no solution for all this except moving out. The partition wall could be lined from the inside. However, the landlord's interest in doing that is likely limited, especially since the neighbors don't perceive it as a problem.