This paper looks at the changes in the vehicle passby measurement techniques over the past decades and provides some insight to the problems faced in developing the technology as well as the product improvements. While all worked diligently to reach a product level, the methods were as varied as the participants. While the us epa started the charge to quieter vehicles the lack of public interest has decreased the us activity to minimal local enforcement. Few products are a major annoyance and little public concern will minimize future programs. World interest is significantly different and the interest of the governments to protect their population from noise polution is very high. This paper will also consider some of the differences that exist in the areas and the impact on noise annoyance.
