With WWII history as a hobby, I have seen a lot of photos over the years, and I do not recall seeing any troops of any nation with any kind of hearing protection. Tank, aircraft, and some naval crews with headphones, but for communication, not hearing protection, although they did affort some small degree of hearing protection.
Classic photos of German tank commanders wearing them with one earpiece off the ear, so they could hear what was going on around the tank are common.
I have read books translated from English (where mechanics are "fitters" and wrenches are "spanners") have mentioned how artillery "gunners" would somtimes shove "cotton waste" in their ears, and I have seen many photos of artillerymen covering their ears with their hands when the big gun was fired.
So I think that hearing protection was seldom issued, and less often actually used in the field in the WWII era.
During my service in the mid 70s, the US Army issued us orange plastic "arrowhead" type earplugs, for use on the firing ranges. While required to have them, actual use was up to the individual, at the whim of the officers and NCOs present. And I can tell you from personal experience that even when worn, they weren't much good when in close proximity to guns with 4, 5, or 6 inch bores...