Dependence of Automotive Sound Levels on Vehicle-to-Microphone Distance

Several independent studies of sound level variation with nominal microphone distance are reported for a variety of equipment types tested in accordance with SAE exterior sound level test procedures. Good correlation between levels and distance is shown, although dependent on equipment type and mode of operation. It is concluded that predictions of sound levels at distances closer to the source than the normally-specified microphone distance can be made with reasonable accuracy.