Earplugs are almost ALWAYS a good idea. Permanent hearing loss is horrible, and tinnitus is as awful as BlastOffMike says.
I found a great compromise for hearing protection.
[ame="http://www.amazon.com/Etymotic-Research-ETY-Plugs-Protection-Earplugs/dp/B0044DEESS/ref=sr_1_7?ie=UTF8&qid=1435188087&sr=8-7&keywords=earplugs"]http://www.amazon.com/Etymotic-Research-ETY-Plugs-Protection-Earplugs/dp/B0044DEESS/ref=sr_1_7?ie=UTF8&qid=1435188087&sr=8-7&keywords=earplugs[/ame]
[ame="http://www.amazon.com/DownBeats-Reusable-Fidelity-Hearing-Protection/dp/B00A3Z44R2/ref=sr_1_19?ie=UTF8&qid=1435188294&sr=8-19&keywords=earplugs"]http://www.amazon.com/DownBeats-Reusable-Fidelity-Hearing-Protection/dp/B00A3Z44R2/ref=sr_1_19?ie=UTF8&qid=1435188294&sr=8-19&keywords=earplugs[/ame]
Either of these are great for reducing wind noise just enough to protect your hearing and not be unpleasant. I have the DownBeats, and they work great. You can still hear everything, just toned down slightly.
Wind noise will vary from person to person, even with the same helmet. Variables such as your bike, clothing, height, head shape all affect noise, and what is quiet for one person might not be quiet for another. Earplugs, on the other hand, always work.