Measurement methods for sound insulation of windows

摘要

The sound insulation performance of window sashes is usually determined in accordance with laboratory measurement method such as ISO 140 -1, -3 (sound pressure method), butrnmeasurement method using sound intensity have also been used recently. The results of these two kinds of test methods cannot be compared without using the Waterhouse correction. For field measurements, on the other hand, a loudspeaker method in accordance with ISO 140-5 should be usedrnto estimate the apparent sound reduction index of windows. In the pressure method, both sides of thernwindow are reverberant sound fields, while under field conditions the indoor side is assumed to have arnreverberant sound field and the outdoor side is assumed to be a free field. In our new test facility thatrnhas a movable receiving room, different measurement methods were used to estimate the sound insulation performance of a sample window under the same mounting condition. As the result, we found that measurements obtained using the sound intensity method agreed with those obtained using the sound-pressure method as long as the Waterhouse correction is used when comparing the results obtained at low frequencies. We also found that the Waterhouse correction should be applied to the results obtained by the field measurement method specified in ISO 140-5. We also report the incidence angle dependence of the sound insulation of windows.