ditto on foam ear plugs.
there are industrial ones that have very high NRR (noise reduction rating), up to 32, but if you wear a 3/4 or full helmet, you may not need that high a NRR.
for greater comfort, look at your drug store for ear plugs marketed for sleeping.
there are also custom fit ones available for reasonable cost.
You may want to check your local traffic laws. There are some areas where ear plugs are prohibited while driving. Doesn't make sense to me, but that's the facts.

I find I can hear horns, sirens, trucks and cars better with ear plugs in, blocking all the wind noise.

duke
loud horns save lives