Various SAE vehicle sound level measurement procedures require use of a sound level meter which meets the Type 1 or Type 2 requirements of American National Standard Specification for Sound Level Meters, S1.4-1983, or an alternative system which can be proved to provide equivalent test data. The purpose of this 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. 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 recommended practice is to establish guidelines which permit the test engineer to insure equivalence of sound data acquisition systems to a sound level meter. It requires that the test engineer have a working knowledge of the characteristics of the sound data being measured.