You would have a helmet on top if you're driving a motorcycle or bicycle, extra 20 dB is easily had with the right design, plus attenuating wind noise. Combine

You would have a helmet on top if you're driving a motorcycle or bicycle, extra 20 dB is easily had with the right design, plus attenuating wind noise. Combine the two and it gets almost safe level of noise. And a car would have pretty decent internal damping. The general traffic is already way too loud. Can reach 80 dBA and even more in tunnels.