I'm glad others have questioned helmets possibly being more noisy than back in the 70's. I think that too. My Nolan N103 is nasty loud. The Schubert C3 is way better. But, Not what I would expect. One of these days I'm going to take the time to work on the Schubert. I know for a fact that sealing the neck reduces the noise level. I can do so with my hand while riding.
That all being said. I ditched the earplugs and have gone to noise reducing Earbuds. They allow me to hear the phone conversation better than I could with the Scalia G9 speakers and foam earplugs.