When I first was getting into motorcycles, I had an older ****'s angle member tell me to never have a quite bike. His reasoning was that people in cars will hear you before seeing you. And every time anyone asked me why I like mine loud, I ask them, did you hear me or see me first? And I always get the I heard you first answer.
I always find fault with that logic, its a heated debate, but I do not think louder is any better. Many times while in my car going down interstate, there's a loud hog behind me... and I don't hear it.
In front of me, yes, I can hear them. But behind, or even in my blind spot, I can not hear them with my windows up and radio at a sensable level. As soon as they get just in front of me, like past my side mirrors, I then can hear them, they can be 10 car lengths ahead of me and can still hear them, but in the most important spot, blind spots, sound means nothing.
Doppler Effect at work. Dang science.