scope:

This Recommendation applies to band filters commonly known as octave, half-octave and third-octave band filters of the passive or active type, the latter including amplifier elements, e.g. tubes, valves and/or transistors. It specifies the most important characteristics of these filters together with the corresponding tolerances. The object of the present Recommendation is to specify the characteristics band-pass filters to be used in sound and vibration analysis for which octave and third-octave band pass-filters are prefered. To permit a comparison of the results of measurements in which band filters are used, it is necessary to use filters having certain well defined characteristics, such as limiting frequencies (cut-off frequencies), selectivity, attenuation, terminating impedances.