Building elements, small: Sound insulation, intensity scanning under laboratory conditions (NT ACOU 093)

  • Report #: NT ACOU 093
  • Approved: January 1995
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This Nordtest method specifies a laboratory sound intensity scanning method of measuring the airborne sound insulation of such small building elements as are defined below. This method also establishes directions about reporting and applying such test data. IS0 140-10 specifies a laboratory method of measuring airborne sound insulation of small building elements under diffuse field conditions. This Nordtest method is primarily intended to be used instead of IS0 140-10 whenever the flanking transmission prevents accurate measurements according to IS0 140-10. The correction of flanking transmission, used in IS0 140-10, is not needed in this Nordtest method. Increasing the number of test objects to avoid inaccuracy due to flanking transmission, used in IS0 140-10, is not used in this Nordtest method. Increasing the number of test objects may, however, be used to evaluate the standard deviation of the results and to increase the accuracy of the results. IS0 140-10 is to be preferred to this Nordtest method when it is not possible to get a low enough field indicator in the receiving room, when the air flow from the building elements to be measured prevents accurate intensity measurements or when the flanking transmission causes no problems. It is intended that the results obtained will be used to develop building elements with appropriate acoustical properties, to classify such elements according to their sound insulation properties and to estimate their influence on the sound insulation of partition constructions in buildings. This Nordtest method applies to building elements with an area of less than 1 m* which occur in a certain number of discrete sizes with well-defined lateral dimensions. The elements are such that they transmit sound between two adjacent rooms or between one room and the open air independently of the adjoining building elements. The method does not apply to windows and doors, and elements with air flows over 2 m/s through the measurement surface. Some examples of equipment covered by this Nordtest method are transfer air devices airing panels (ventilators) outdoor air intakes electrical cable ducts transit sealing systems (e.g. sealing systems for passings through walls or slabs). This method is not primarily intended for components that constitute part of an integrated unit for which the associated sound transmission might depend on an interplay of components.