SAE J192:2019 pdf free

SAE J192:2019 pdf free.Maximum Exterior Sound Level for Snowmobiles
The applicable reading shall be the highest sound level indicated for the run, between the start point and the end point, ignoring unrelated peaks due to extraneous noises or surface irregularities. Measurement runs can be repeated to eliminate irregularity effects.
Test runs shall be repeated until three readings within a 2 dB range per snowmobile side have been obtained. The sound level for each side of the snowmobile shall be the average of all three readings, rounded to the nearest integer. The sound level reported shall be that for the side of the snowmobile with the highest readings after environmental corrections have been applied as described in Section 6.
An omnidirectional sound source with known acoustic properties should be used to measure the sound propagation properties of the environment. The sound source should be evaluated to obtain a known sound power level for each 1/3 octave band from 100 to 1000 Hz following ISO 3741. The field measurement of the sound source’s sound pressure level should be performed regularly throughout the testing session as changes in air temperature distribution from the ground upwards, wind, and humidity as well as snowmobile traffic will change these measurements. The source should produce broadband noise in the frequency range from 100 to 1000 Hz, and is to be placed in the center of the snowmobile path with its center 500 mm (20 inches) above the surface and a 1/3 octave sound spectrum measured. The 1/3 octave measurement for the speaker should be a linear average across a 10 second time window.
Assuming an ideal sound propagation with a monopole source located on the ground surface, the sound pressure at the measurement point can be calculated from the known sound power of the acoustic source at each 1/3 octave frequency using Equation 1. The speed of sound and air density calculations are functions of air temperature, barometric pressure and relative humidity. The speed of sound calculation is presented in Equation 2 from the reference of 2.1.4. The air density calculations are presented in Equation 3 from the reference of 2.1.4 respectively.SAE J192 pdf free download.