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Evaluating Ceiling Acoustics
OTHER PARTS OF THIS ARTICLEPt. 1: Evaluating Ceiling FinishesPt. 2: This PagePt. 3: Evaluating Ceiling LongevityPt. 4: Evaluating Ceiling Sustainability
Another look that continues to be popular is an open plenum design. While exposing the ductwork is trendy, the acoustical problems that then arise are well known: With nothing to stop it, sound reflects off of the hard deck and can become disruptive.
“Clouds” and “canopies” are among the ceiling treatment choices that preserve the open plenum look while providing acoustical benefits. These are “free-floating” ceilings that add sound absorption to the space, says Davis Brayman.
There are many benefits to a quieter space. For example, research has shown that in health care, a quiet environment can speed recovery times.
Speech privacy is another consideration. When specifying the ceiling, know who is working in the space and what their work requires. In private offices, ceilings with a higher ceiling attenuation class (CAC) rating can help prevent sound from bleeding into adjoining spaces. A CAC of 40 will reduce sounds transmitted by 40 decibels (dB).
In open plan spaces, a ceiling with an articulation class (AC) rating of 180 and a noise reduction coefficient (NRC) of .80 or higher will help speech privacy, says Davis Brayman. AC measures the acoustical performance of products in open plan spaces, while NRC measures average sound absorption, rated from 0 to 1.
Soundmasking can further augment speech privacy in open plan spaces. Though the idea of injecting sound into a space might seem counterintuitive when so many other efforts are being made to make the space quieter, soundmasking systems help spaces hit the sweet spot between too loud and too quiet.
Soundmasking systems produce a steady background sound tuned to the normal speech spectrum, decreasing speech intelligibility and softening regular office noises. Maintaining background sound levels between 42 and 48 decibels fosters privacy without being disruptive.
The most common application for soundmasking systems is through ceiling-mounted speakers. However, they can also be located in access floors, in open plenums, and even on office furniture and partitions.