Measurement of Light Vehicle Exhaust Sound Level under Stationary Conditions
|Publication Date:||1 July 2007|
This SAE Standard establishes the test procedure, environment, and instrumentation to be used for measuring the exhaust sound level for passenger cars, multipurpose vehicles, and light trucks under stationary conditions.
Measurements are taken under steady-state conditions. In this respect, this procedure differs from ISO 5130 which includes measurements under the dynamic conditions of an engine deceleration.
This sound level measurement procedure has been developed as a guide for governmental agencies establishing vehicle in-service sound level regulations and enforcement measurement procedures. It is directed at the assessment of vehicle exhaust noise and is not intended to determine maximum vehicle sound levels. (See Appendix A.)
Technology changes have occurred that make the SAE J1169 procedure inadequate. SAE J1169 is a legacy test that specifies 3/4 maximum rated engine speed (MRES) as the test condition. Many modern engines will not allow 3/4 MRES in neutral and/or have fuel cut-off software that prevents the engine from reaching this target. Additionally, the measurement technology of slow exponential time-averaging characteristic is outdated as compared to the fast exponential time averaging characteristic used in SAE J1492. For these and other reasons, SAE J1169 will be superseded by SAE J1492, which provides a continuous measure of exhaust system sound level over a range of engine speeds.