It also explains why it is nigh impossible for francophones to learn another language past a very early age. We simply do not hear what you say. We would understand it, we simply, literally, can't hear you. We hear you no more than you hear sub-sonic whale sounds, or high pitched mice. Our ears do not register the sounds you are producing.
This is so true. When I was in France, no matter how loud I shouted at them and no matter how vigorously I waved and flapped my arms about, they just couldn't understand my English.

I wouldn't mind but I got an 'O' level in French. Mind you it was 35 years ago.