Uncertainties in standard impact sound measurement and evaluation procedure applied to light weight structures

Paper i proceeding, 2010

A three year research programme has recently started in Sweden, aiming at improving the mutual connection between the perceived sound, vibration and springiness and their corresponding measured values in lightweight structures. The main goal is to describe new objective measures of assessing the acoustic quality, with the expected result that the experienced sound, vibration and springiness are not dependent of structural bearing system in the building any more. The consequence of new methods will be that various structural systems within one certain sound class in a classification scheme will provide fairly equal evaluation with regard to subjective response. The research programme, Aku- Lite, is divided into seven work packages (WP). Initial results from one work package (WP 4), related to current subjective and objective field data are presented in this paper. The aim of topical part of the study is to investigate the liability of measurements results and evaluation procedure when those are carried out in accordance to ISO 140 and ISO 717. It involves an initial inventory and analysis from objective measurements, according to ISO 140, performed on light weight structures on the field by various consultants in Sweden. The study considers principal problems with current standards, affecting each operator performing field measurements in light weight structures and thereby impacting the final result quality. Typically, the measured sound pressure level and the reverberation time differ a lot in low frequencies, compared to heavy structures. The measurement result (distribution) between various measurement positions is rather random in the low frequency region, i.e. there is no typical pattern for light weight structures in general. The complexity of different light weight structural bearing systems and their sensitivity in the low frequency range requires a more rigid description of the measurement and evaluation procedure. The lack of objective sound and vibration data below 50 Hz is also a problem since subjective disturbance often emanates from this frequency range. Copyright