I have a set of noise cancelling Sony MDR-1000X (previous generation) and just having the headphones switched on without music playing, they don't do much to bl

I have a set of noise cancelling Sony MDR-1000X (previous generation) and just having the headphones switched on without music playing, they don't do much to block voice. However if I play music quietly I can't hear anything, even if someone is talking right next to me (or at me).