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This paper-bound booklet of 75 pages is an up-to-date breviary on practical acoustics as applied to hearing aids and audiometers. There is an effort almost identical with that put out by the Harvard group to determine ideal standards for a hearing aid suitable for general use. (The socialist government has already under way the manufacture, under contract, of a standard aid which is dispensed gratis to the hard of hearing. The pamphlet contains a considerable amount of scientific data that have been worked up by acoustic engineers and the book re-sembles in this respect the reports from the Bell Laboratories, the American Standard Association, the Research Council, the American Acoustical Society and similar literature published in the United States. As a matter of fact, many of the matters described were initiated in this country—standardizing audiometers, testing the performance of hearing aids, construction of the artificial ear. It is notable and