Originally Posted by MMACH 5

You're making an assumption about how "tuned in" a deaf or hearing person is to their surroundings.

Sound is quite an unreliable means of judging traffic around you. Speed differential means that by the time you hear an overtaking car, it is too late to react. And our forward-facing ears mean that we can't tell from the sound whether the car approaching from behind us is in our lane or the other lane. These two shortcomings mean sound is nearly a worthless form of traffic monitoring.

If you're riding on a multi-use path with pedestrians and other cyclists, your ears can play a much bigger part of what is approaching and whatnot.