Got my challengers tonight. Rode them a few miles with the MP3 player and a few miles with the Satelite radio. The sound is great (not doing an audiophile comparison to my Mirage speakers but compared to other mobile forms of music they are so superior to others I've tried it'll take me a while to get used to them before I can make even a minor criticism). The wind noise is reduced to an occasional whoof...!!! I can still hear the bike, the traffic, and things around me,although quieter. Before heading out on the bike I put them in and checked my e-mail. Sitting here at the computer I could hear the wine cellar cooler start behing me. What that shows it that your ears have a tremendous ability to discern DIFFERENCES in acoustic level, even it it is low dB vs very low dB.
The only problem is that the helmet makes my ears uncomfortable with them in. I'm between a medium and a large (22.75 in circumference) and I have my head squeezed into a med helmet. I've been thinking of trying a Large as perhaps more comfortable so this may be what does it for me. I'll take them to a bike shop tomorrow and try some helmets one.