Having ridden motorcycles since I was 11 years old (I am 69 now), and still riding a Honda Gold Wing today, I can speak a bit about riding bikes.
1. There is absolutely NO interference with hearing, when you wear any motorcycle helmet. That is a bunch of bull manure, by those that don't want to wear one.
2. There is no restriction of vision, by any properly fitting helmet.
3. Anyone that wishes to ride a motorcycle without a helmet should be allowed to do so, PROVIDED that they can show proof of a $1,000,000 accident insurance policy that covers themselves and any rider for injuries sustained in an accident.
I was taught to ride by a World War I Dispatch Rider. The first month, he taught me how to lay a bike down, without getting badly injured. As he taught me, "you always ride figuring that the people in cars are really TRYING to kill you".
I have ridden virtually every kind of bike made in the USA, Germany or Great Britain since the 1930's over the years. I have owned Indians, Harley's, BSA's, Norton's and Honda's.
Anyone that rides without full protection is an idiot in my opinion. I wear a full face helmet, and have since the 1960's. I have never had the slightest problem hearing others, seeing, etc.