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In aerospace applications it is often vital to understand what is happening when analyzing sound and vibration data and what total accuracy one receives. The tradition has been to spend money on yearly calibration of sensors and part of the measurement equipment, but not on the software used for analysis of the data collected by these sensors. While the sensors might be accurate to a percentage level, erroneous analysis procedures can give arbitrarily high errors! Usually, there is no “calibration option” or “benchmark” for sound and vibration analysis software. This paper will present some common pitfalls and what can happen if the user is not aware how the software is handling the data, or even worse, the code was not correctly implemented in the first place. Some real life examples of the latter and suggested solutions to avoid such harmful situations will be presented.

Commercial tools for measurement and analysis of noise and vibration signals have traditionally been very expensive. In the last decade, however, multi-channel measurement systems have become relatively inexpensive. The analysis functionality in most inexpensive instruments is limited. Therefore, many companies are using alternatives for post processing of measurement results. Matlab is a platform that is popular for this purpose and which offers many advantages over dedicated, menu driven systems. The open functions in Matlab assure flexibility and the possibility to modify functions for specific needs. In addition, a command based programming environment provides for traceability and quality assurance, including qualification of used algorithms, important aspects particularly in the aerospace industry. In the past, basic functions for signal analysis and vibration analysis have had to be developed before taking full advantage of the Matlab platform.