This SAE Recommended Practice establishes the instrumentation, test site, and test procedure for determining the maximum exterior sound level for snowmobiles. Sound propagation is directly related to the ground cover and provides the largest variation to the measured result. A correction factor is introduced to improve year round test repeatability of the results on grass surfaces by correcting their spectrum to be similar to snow covered spectra. Measured sound pressure levels are also highly dependent on the degree of track slip present when performing the vehicle acceleration. Operators should attempt to limit track slip as much as possible while maintaining the requirements described in 5.1.1.
The committee has agreed upon increasing tolerances on entry speed and full throttle position to reduce the amount of test runs needed to satisfy requirements. These increases in tolerance do not change the highest sound measured for the test.