This new procedure attempts to determine the average sound pressure level of a snowmobile during typical trail operation. It consists of averaging a steady vehicle speed SPL with a wide-open throttle acceleration SPL. Weighting is applied on both SPL prior to averaging. This new standard defines a sound level value that is more representative of general public perception. Reduction of the sound level emitted by a snowmobile based on this method would translate to a higher acknowledgement by the general public.
The weighting factor determination is based on ISO 362-1:2015 used to determine the urban sound level of motorcycles, based on vehicle power to mass ratio (PMR). The PMR of currently available snowmobiles ranges between 75 and 400. That range of PMR yields to weighting factors ranging from 42.5 to 52.5%. Using a median value of 47.5% for all models introduces an error in the order of 0.5 dBA and therefore is used in this document to simplify its use.