What we currently refer to as high cut helmets were once commonplace. For instance, during the Roman era, many versions of the Galea or helmet featured cut outs for the ear.
(photo from Roman Hideout)
Even in the modern era, the US Army experimented with the concept during the Vietnam conflict.
This photo, taken in August, 1969 at Camp Pickett, VA, depicts a Soldier wearing a Lightweight Individual Clothing And Equipmen (LINCLOE) helmet prototype. Several versions were evaluated, made from nylon or titanium.