Interesting discussion. I have been wondering about this, as it is commonly believed among motorcyclists that the act of riding a motorcycle, even with a full coverage helmet, eventually causes hearing loss due to the constant wind noise. When I rode my duc daily I started wearing earplugs, and found that my concentration levels improved; suggesting to me that my brain was tiring itself somewhat dulling all that wind noise. (or maybe it was the sweet sound of the intake honk and open airbox, but I digress...)

On days where I car/bike commute I have occasionally forgotten my helmet. I notice that wearing a helmet (at least, MY helmets a Bell and a Trek) increases apparent wind noise. I do believe there is enough constant wind noise to put me close to postential damage as I ride nearing 2 hours a day.

I just haven't tried HearO's yet, but I will. I'll post again after a few trial runs.