I too have never heard the siren of a police car or ambulance in my life. Even when I was HOH with no aids, or HOH with aids. My driver's ed teacher was the best. He understood my hearing problem and had specialized instruction for me. I was taught to be ever vigilant with my mirrors and such. My windows are totally uncluttered and all, so I can see everywhere.
Just today, I had to pull off to the side. A police car was behind me, saw that I put on my flashers and pulled over to stop (Florida law). He pulled in behind and came up to ask if I had a problem. I said, look behind you, he then saw the 3 fire trucks, and 4 ambulances all rushing by. He said, how did you hear those, I said I am deaf and instead I saw them. He was surprised and pleased. We then went on our merry way.