Today, when heading into the wind, there was a low-pitched whooshing noise in my right ear that was actually painful. I stopped and put those twists in my helmet's straps. It certainly seems to help. So for now maybe I can skip the cat-ears and save the money. If I find later that twisted straps aren't sufficient, I can try the cat-ears.
Speaking of wind, my long ride got tough today when heading back home. The wind got as strong as 16 mph, which for me is a lot of wind resistance during a long ride. I'm glad I read about that helmet-strap trick, or my ears would have been miserable.