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.
Rationale: SAE J192 “Maximum Exterior Sound Level”
It is proposed to substitute
“The method has been found to have a measurement uncertainty of ±2 dBA for well maintained snow surfaces and ±2 dBA for grass surfaces with the inclusion of the correction factor.”
“The maximum A-weighted sound pressure level indicated during each passage of the vehicle between start point and end point shall be reduced by 2 dB(A) to account for measurement inaccuracy and mathematically rounded to the nearest first decimal place (e.g. XX.X) for both microphone positions.”