Helmets in Pathfinder/3x

I was stewing on the issue of helmets a while back and came up with a set of rules that add verisimilitude to the existing helmet rules without too much complexity.

All armor is assumed to come with an appropriate helmet. However as helmets make it much harder to see and hear, subtract all armor check penalties from perception rolls,

All abilities that reduce armor check penalties (class abilities, masterwork, magic etc) also reduce this penalty.

If a character chooses not to wear a helmet, perception penalties may be ignored however reduce armor class vs confirmation of critical hits by four to a minimum of 10.

Magic helmets work normally as per armor.

So what do ya think?