The study was just stupid. You can't hear exhaust because it is pointed the wrong direction!? It is like these idiots don't even know sound travels in all directions far faster than any vehicle.
I guess you can't hear fire engines or trains coming either because you are playing music at 100 decibels with your sound cancelling headphones on. Just dumb.
One time I was in a parking lot backing up when I heard a Harley and came to a stop. Avoided an accident. Numerous times driving on the highway getting ready for a lane change when I noticed a sound and double checked my blind spot. Surprise, a motorcycle was there.
Texas, the pedophile state. Don't like it? Maybe get some new reps!