From what I understand, they are reaching the ear, but there is noise being applied on the opposite spectrum to cancel the noise out? Think of sound as a wave in a graph, it goes up and down. From my understanding active noise cancelling is just seeing where that graph is and playing(?) A sound the opposite of that exact wave lenght and therefore canceling it out? So you don't hear it . I may be completely off here this is just what was explained to me and until this second I took it as well okay that's how that works.