Objectif
The intercomparison that was studied deals with laboratory measurements of the sound insulation of double glazed framed windows. The aim of the project was to determine the measurement precision associated with a measurement procedure better defined than the one in the present ISO Standard 140/3. Measurements were carried out on 2 windows that had different kinds of glazing. The measurement guidelines referred to the ISO standard and, additionally, described in detail the 2 source positions and the mounting conditions. Measurements were also required to be made at frequencies lower than 100 Hz in preparation for a possible extension of the ISO standard to low frequencies.
It is concluded that, in general, a reasonable agreement can be achieved when the source positions and the mounting conditions are prescribed. However, large variations can arise for test objects having strong resonances, and for low-frequency measurements. In these cases, variations in the room geometries have a dominant effect.
PROJECT MTR00127 PROJECT DEFINITION A previous intercomparison was carried out on double glazing panel without frames. The results showed that when applying uniformly a well defined procedure, 12 laboratories agreed to within 1dB with Sd = 0.3 dB. This represents a 3 fold improvement of the level of agreement commonly encountered before. Two laboratories which do not conform to the specification for the construction of the wall and aperture had low and high values. As was indicated in project 078, the conclusions of this work were introduced in the ISO standards. As a necessary follow up, an intercomparison is made of the noise attenuation by windows with frame.