Use of recompressed impulse response to identify sources and paths of structure-borne noise in wide flange I-beams and pipes conveying fluid

Abstract

A procedure is described for identifying sources and paths of structure-born noise in structures built up from wide flange I-beams, as well as piping systems conveying compressible and incompressible fluid. The use of impulse response or modified impulse response to estimate time-delays frequently is of little value because the wave propagation is dispersive. With reflections present, it is impossible to distinguish and identify the wide peaks. If one can establish the dispersion law, namely, the relation between frequency and wave number, one can “recompress” the impulse response in a certain sense, with respect to length of paths. The peaks are fairly narrow and one can identify noise paths. A discussion is given for various dispersion relations, together with theoretical justification and practical implementation. Some experimental results are given.