Measurement of sound emission from military off-road vehicles driving on a curved path

摘要

The Norwegian Defence in cooperation with the Norwegian Defence Estates Agency evaluates and controls noise levels from all activity on military training ranges. One such activity is noise from military off-road vehicles. Emission strength is usually determined by some sort of pass-by test, as conformed by the automobile industry. In such tests the vehicle will drive on a straight line past a microphone. However, this is not relevant for off-road military vehicles, where the levels found from standard pass-by tests are lower than levels during normal operation. For a battle tank normal operation may consist of driving up a steep curved path in very uneven terrain. One way to find better emission levels is to go out and measure noise levels under normal operations. This, however, introduces a complicating factor. Since the vehicle is no longer traveling on a straight line, the usual methods to find the distance from the microphone to the vehicle will not work. To deal with this a modified pass-by system was put together in connection with Brüel & Kjær, where an accurate GPS-system tracks the position of the vehicle. This paper describes the GPS-based pass-by system and some experiences during operation.