When I was riding my 2007 ninja 250 to work on the highway super early in the morning ~75mph or so I was mostly okay without ear plugs. The air was nice and clean and my helmet seemed fine. I probably should have worn plugs then anyways.
Once I changed bikes over to a vstrom 650 I got myself some of those "vibes" earplugs and now wear those whenever I'm going to be on clear highway. For traffic during commuting I typically don't bother as I'm not rarely breaking 50mph.
https://www.amazon.com/Vibes-High-Fi.../dp/B018WPOQSG