Secondary Window System Sound Transmission Loss Test Certificate
On this page you can see our “Secondary Window System Sound Transmission Loss Test Certificate” (29 October 2012) showing the results of a test we commissioned from Day Design Pty. Ltd. for one of our secondary double glazed windows fitted with 6.38 mm laminated glass and pile seals.
It shows for a Sound Reduction Index of 45 dB (45 decibels) … which by the way, is a lot!
You can click on the image to download a PDF of the certificate if required.
Sound Reduction Index
The sound reduction index is used to measure the level of sound insulation provided by a structure such as a wall, window, door, or ventilator.
The Sound Reduction Index is expressed in decibels (dB). It is the weighted sound reduction index for a partition or single component only. This is a laboratory-only measurement, which uses knowledge of the relative sizes of the rooms in the test suite, and the reverberation time in the receiving room, and the known level of noise which can pass between the rooms in the suite by other routes (flanking) plus the size of the test sample to produce a very accurate and repeatable measurement of the performance of the sampled material or construction.
Weighted Difference level (Rw)
The most basic index is the Weighted Difference level Rw. This index is defined by measuring in decibels (dB) (according to AS 1191-2002), the noise level produced on each side of a building element under test (e.g. a window) when noise is produced in a room on one side (or outdoors) & measured both in the room where the noise is produced & in the room on the other side of the element under test.
The measured levels from the source room (or area) are then compared to the measured levels in the receiving room, and the difference is taken.
This produces a measured difference level for each frequency band in the measured spectrum.
To produce a single integer number the measured spectrum is plotted on a graph, and compared against a reference curve (defined in AS/NZS ISO 717-1:2004 for airborne sound insulation). The reference curve is moved steps until the total of the unfavorable deviations (measured points on the graph below the reference graph) is as close to 32 as possible but not greater than 32.