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Although the ranges in which pneumotachographs evidence linear output to static flows are documented in the literature, output reliability or the stability of calibration functions resulting from the input of dynamic nonsinusoidal flows (such as those which occur during nasal breathing) have not been investigated. Furthermore, it is not known whether the type of requisite pressure transducer used in conjunction with the pneumotachograph influences the pneumotachograph's linearity, output reliability, or dynamic response. To provide information on these points, the authors determined the dynamic and static responsiveness of three pneumotachographs commonly used in rhinomanometry, in combination with three requisite pressure transducers. Experimental data indicate that: (a) output reliability depended on the pneumotachograph-pressure transducer combination and was not readily predictable from the reliabilities of the individual components, (b) heating increased pneumotachograph reliability, and (c) differences in accuracy existed among transducer combinations of high, but not low, flow frequencies.