Five Nordic laboratories have carried through an intercomparison concerning laboratory measurements of sound insulation at low frequencies. Measurements have been carried out on two different test objects – a sandwich steel plate and a window - in the frequency range 50 Hz to 160 Hz according to ISO/DIS 15186-3, which describes a new test method based on intensity technique.
As a mandatory part of ISO/DIS 15186-3 a qualification of test facilities and test procedures shall be performed in each laboratory. All laboratories carried through this qualification test successfully. The reproducibility of the measurements on the two test objects was satisfactory. The sound insulation of the window was in addition measured according to ISO 140-3 in the frequency range 50 Hz to 5000 Hz. A considerable deviation between the results was seen at the frequencies 50 Hz to 80 Hz. In the frequency range 100 Hz to 3150 Hz the reproducibility in general fulfilled the estimated values stated in ISO 140-2.