Acoustics

Myths, Lies and Decibels!

The performance of an Operable Wall is measured in a laboratory and expressed by its weighted Reduction in sound, Rw. The single Rw figure is a composite rating of sound reduction at frequencies from 100 Hz (Hertz) to 3150 Hz, when compared to an Australian standard line.

• Don't get hung up over one or two Rw's. Some manufacturers play a numbers game. "Mine is 1 Rw more than yours!". The human ear can't discern a 2 Rw difference, and even laboratory results can vary by 1 Rw depending on the conditions.
• Beware of U.S results. They can be 10% higher than tougher Australian testing. Also be aware that Rw is a more stringent measurement than simple, speech frequency averages.
• Ensure test results are reasonably recent and are from reputable laboratories like RMIT or CSIRO. Laboratories with non-standard testing protocols do exist both in Australia and overseas.
• Thin light panels are unlikely to be as effective as thicker heavier panels. There is no magic to acoustic performance and weight is a key factor. Check the test reports to be certain.

Our Testing

It's very good and it's been done recently at the RMIT, one of Australia's leading laboratories to AS 1191-2002, which makes it BCA compliant. In tests up to Rw53 we use sweep seals at the top and bottom of the panels, demonstrating that retractable seals are not required for acoustic reasons for anything other than the highest rating. Lotus offer Rw38 to Rw55, which allows us to meet your acoustic requirements from budget to high performance and everything in between. Rw55 is the highest result achieved for an Operable Wall in an Australian test.

Note: - It's impractical for any manufacturer to test every combination of product type, configuration, layout, surface finish, etc. Tests are done on benchmark constructions and supplemented by acoustician's opinions if necessary.

Laboratory vs. Real Life

Acousticians measure the performance of an operable wall in laboratories (LAB Rw). In real life even a perfectly installed wall is unlikely to perform as well due to deficiencies of the building. Buildings inevitably have peripheral leakage through airconditioning ducts, carpets, ceiling tiles, etc. which can reduce the FIELD Rw by 10% - 15% below the LAB Rw. Be aware of this when specifying. In critical situations specify both a LAB Rw and a required FIELD Rw or Noise Isolation Class (NIC). Please contact Lotus if you need advice on this.