That really depends on what type of helmet you wear (if at all) since the flow around that dictates the noise levels. It also depends on how your ears are shaped and where the wind is coming from. There's really no way to tell unless you take a head, stick a sound meter where the ear drum is, then measure it.

I just blew air over the sound level meter here with a piece of wax over it shaped like an ear and with a 25mph wind going over it, the SPL was averaging like 90dbA...