Outdoor Signs America Wiring Diagram - You can ask an RV question here. Do you have questions about Recreation Vehicles, Camping or the RV Lifestyle. We will give you the answers to those questions.. I. Introduction. Noise, or unwanted sound, is one of the most common occupational hazards in American workplaces. The National Institute for Occupational Safety and Health (NIOSH) estimates that 30 million workers in the United States are exposed to hazardous noise..