Average vs RMS meters for measuring noise

Abstract

It appears that the controversy is still alive over whether average reading or root-mean-square reading meters should be specified as standard for the measurement of noise. This being the case, it is worthwhile to consider the entire subject from the standpoint of basic fundamentals, to determine what are the significant quantities involved, and then proceed to investigate which type of meter yields the most significant results. The following is the result of such an investigation. The entire discussion rests on 1) an axiom, that energy transfer is the fundamental interaction within the universe, and 2) a premise, that for the type of measurements under discussion (audio), all significant processes are linear. Given these two starting points, the conclusion is reached that the meaningful quantities are found by rms measurements. It is shown further, by concrete example, that measurements made with average reading meters can depart widely from those made with an rms meter. This being the case, it is necessary that measurement standards specify the use of rms meters. Those who elect to use average meters, then, bear the responsibility of determining the accuracy of their results in terms of the fundamentally important quantities.