There are bugs with both the normal version and the reinforced FEMALE versions of the Metal armor helmets

The female model of the helmet, despite not covering the mouth, can still muffle the sound of the wearers speech.

Also the wrong textures are displayed.

more info:
http://fallout.wikia.com/wiki/Metal_armor,_reinforced
http://fallout.wikia.com/wiki/Metal_armor_%28Fallout:_New_Vegas%29