Effect of measurement method on the reproducibility value of the single number quantities or airborne sound insulation

摘要

A proposal for new single-number quantities (SNQ) for airborne sound insulation has been recently presented in ISO CD 16717-1. The proposed SNQs, R_(traffic) and R_(living), are determined within 50-5000 Hz while their present counterparts, R_w+C_(tr) and R_w, are determined within 100-3150 Hz. There is concern that the high reproducibility values of sound reduction indices (SRI) determined by ISO 140-3 below 100 Hz could result in an increase in the reproducibility values of the proposed SNQs. The aim was to compare the reproducibility values of the proposed and the present SNQs. The second aim was to test if the reproducibility values depend on the test method of SRI, i.e. pressure method (ISO 140-3) or intensity method (ISO 15186-3 below 200 Hz). The SRI of a window was measured in five laboratories applying both test methods. The present and the proposed SNQs, and their reproducibility values, were determined according to relevant standards. When the SRI measurement was based on ISO 140-3, the reproducibility values of R_w+C_(tr) and R_(traffic), were 3.1 dB and 3.6, respectively. Similarly, the reproducibility values of R_w and R_(living) were 1.5 and 2.1 dB, respectively. When the SRI was based on intensity method below 200 Hz, the values changed from 1.5 to 1.9 dB and 2.5 to 2.1 dB, respectively. Based on these results, the inclusion of frequency band 50-80 Hz to the most important SNQs, R_(living) and R_(traffic) is not supported because it will increase the uncertainty of the SNQs compared to R_w and R_w+C_(tr).