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Abstract
Since 1952, there have been certain qualitative standards for hearing aids. In 1963, the standard was revised and extended afresh to include newer types of aids. By 1969, it was evident that a total revision of the existing standards was in order. In this study, the author explains the essence and spirit of this new project principally based on verifying that aids meet the stated standards as supplied by the manufacturer, and which comprise, among others: the frequency response curve, the mean acoustic gain, the harmonic distortion, the maximum level of output and the noise level. To these purely electroacoustic characteristics are added several tests under various climatic conditions. The methods of measuring these characteristics are not discussed in this study, as they are precisely stated by the IEC recommendations No. 118 and 126.