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This SAE Recommended Practice sets forth the instrumentation, environment, and test procedures to be used in measuring the silencer system effectiveness in reducing intake or exhaust sound level of internal combustion engines. The system shall include the intake or exhaust silencer, related piping, and components. This procedure is intended for engine-dynamometer testing and is not necessarily applicable to vehicle testing (see Appendix A). The effect of the exhaust or intake system on the sound level of the overall machine must be determined using other procedures. This procedure may be successively applied to various silencer configurations to determine relative effectiveness for that engine. Insertion loss for individual silencers may be calculated through measurement of the silenced and unsilenced system.

Various SAE vehicle sound level measurement procedures require use of a sound level meter which meets the Type 1 or Type 2 requirements of ANSI S1.4-1983 (see 2.1.1.1), or an alternative system which can be proved to provide equivalent test data. The purpose of this SAE Recommended Practice is to provide a procedure for determining if a sound data acquisition system (SDAS) has electro-acoustical performance equivalent to such a meter. By assuring equivalent performance of the test instrumentation, the equivalence of test data is assured. Two general configurations of sound data acquisition systems will be encompassed (see Figure 1). The first configuration consists of instrument sections which perform as a sound level meter. The second configuration is a system which records data for later processing. The intent of this document is to establish guidelines which permit the test engineer to insure equivalence of sound data acquisition systems to a sound level meter.

Various SAE vehicle sound level measurement procedures require use of a sound level meter which meets the Type 1 or Type 2 requirements of ANSI S1.4-1983 (see 2.1.1.1), or an alternative system which can be proved to provide equivalent test data. The purpose of this SAE Recommended Practice is to provide a procedure for determining if a sound data acquisition system (SDAS) has electro-acoustical performance equivalent to such a meter. By assuring equivalent performance of the test instrumentation, the equivalence of test data is assured. Two general configurations of sound data acquisition systems will be encompassed (see Figure 1). The first configuration consists of instrument sections which perform as a sound level meter. The second configuration is a system which records data for later processing. The intent of this document is to establish guidelines which permit the test engineer to insure equivalence of sound data acquisition systems to a sound level meter.

The scope of the recommended practice includes the system performance requirements for the entire sound measurement system. It provides the methods needed to verify Type 1 or Type 2 instruments. However, it also provides a method to qualify a SDAS that does not meet the requirements in their entirety, but can be used provided knowledge of the test data is obtained and an iterative process is followed in qualifying the SDAS. The system need only be qualified for the dynamic characteristic and weighting mode in which it is to be used. The scope of this document does not include qualification of system components for harmonic distortion, tape recorder wow and flutter, etc. However, these factors must be considered when determining system performance, especially where spectral information is sought. The references in Section 8 should be consulted for general performance requirements and precautions regarding instrumentation for acoustical measurements.

This SAE Recommended Practice establishes the test procedure, environment, and instrumentation for determining the maximum exterior sound level of highway motor trucks and truck tractors over 4540 kg gross vehicle weight rating (GVWR) with governed engines under stationary vehicle conditions. The basic procedure involves a full throttle engine acceleration and a closed throttle deceleration with the engine inertia as the load.

This SAE Standard establishes the maximum sound level for passenger cars and light trucks and describes the test procedure, environment, and instrumentation for determining this sound level.

This SAE Standard establishes the test procedure, environment, and instrumentation for determining the maximum sound level for passenger cars and light trucks.