I raced 2 cycle karts for 15 years in the 70-80s without earplugs. Now I need hearing aids to raise the mid frequencies (voice range) when I bother to wear them.
When I returned to riding in 2008 I rode a while without plugs and the intercom was nearly impossible to decipher. I switched to earpeace musician plugs and they do an excellent job of reducing wind & road noise but allow the voice range thru so I hear better at speed.

I am more observant than average and I use my vision, mirrors, (and revolving head) to assess the surroundings regardless of transport.

Now if only I could find earplugs that cancel LOUD PIPES!