I had tinnitus symptoms earlier in the year in my right ear and it lasted for over a month.
Probably motorbike related as I don't listen to loud music, wear headphones etc.
I know I said my Shoei is quiet by its in relative terms.
I think Caberg make one of the quietest helmets (I forget the model name).
If you are just commuting in town with only a few mins of 60mph roads you'll probably be ok without earplugs.
But prolonged fast road riding with wind noise should be ridden with ear plugs.
Besides, wind noise can be fatiguing too.