Guidelines for the application of the MLS technique in building acoustics and in outdoor measurements

摘要

Measurements in building acoustics basically are used for determination of sound pressure levels and of reverberation times in diffuse sound fields. In some cases free field conditions apply, for instance, in measurements of the sound insulation of facades and in recently developed methods for measurement of sound absorption in situ [1]. The subject of this paper is the calculation of the signal to noise conditions in modern digital correlation measurement techniques compared with conventional techniques. Furthermore, related guidelines for choosing parameters of signal generation and processing are derived. For this purpose the maximum length sequence (MLS) technique is taken as an example. Finally, limitations of the MLS technique due to violation of important prepositions ("LTI systems") are discussed in the light of the applications listed above.