Notes on Some Practical Comparison Tests Made between Several Acoustic Measurement Methods

In considering the various methods used in making over-all acoustic measurements on radio receivers, from the standpoint of possible standardization, it was felt desirable to make a comparison of the results obtainable by the several principal methods now in use in this country. Accordingly a radio receiver was shipped successively to five different laboratories equipped to make such measurements. It was checked between each shipment by a sixth laboratory to guard against changes caused by the shipments. The test equipment setup and method used by each of the co-operating laboratories is described. The results obtained are discussed briefly and typical curves made by each laboratory are shown. The author has refrained from drawing any arbitrary conclusions regarding the relative accuracy or effectiveness of the various test methods employed by the cooperating laboratories. Instead, the comments, which the engineers of each laboratory cared to make on the curves obtained and the methods used, have been given. The reader is thus provided with data and a valuable series of comments from some of the most expert engineers in this field, from which he may arrive at his own conclusions. In general it is felt that the curves show a greater degree of similarity than might have been expected considering the rather fundamental differences in the test methods used, and that certain possibilities in the direction of useful standardization in this field have been indicated.