A face protector includes a one piece shield in which an optical center is displaced away from the normal straight ahead line of sight toward an activity specific line of sight to minimize image shift that occurs when a direction of gaze passes across the edge of the shield. The process includes transesterifying at least one aromatic dihydroxyaryl compound and a diaryl carbonate in the melt in the presence of a catalyst, mixing the melt obtained in step with a foaming agent passing the mixture at 250 to 340\xb0 C. Furthermore, by setting an overlapping amount to not less than 0. It assists less experienced operators by recommending the next command, and it adds robustness to the voice command interpreter by verbally asking the operator to repeat unlikely commanded actions. A receiving unit is mounted proximate to the rake.