A protective helmet including an outer shell including at least one aperture, an elastomeric diaphragm connected to an inner surface of the outer shell and covering the at least one aperture, an inner shell slidingly connected to the outer shell where the inner shell is spaced apart from the outer shell, and at least one expandable bladder positioned between the outer shell and the inner shell and operatively arranged to displace the elastomeric diaphragm in the at least one aperture of the outer shell.