Open Plenum Can Lead To Sound Challenges

  June 4, 2013

Acoustical design is an element in an overall green design, and acoustic properties of tiles are an important piece in controlling noise in a building — one element of indoor environmental quality. But green interior designs can sometimes create additional problems for acoustical engineers as they try to control sound.

The problem comes when ceilings are eliminated in favor of an open-plenum approach. While that strategy does reduce the use of materials, it also introduces acoustical problems. In the ABC equation for improving acoustics — absorb sound, block sound, and cover sound — ceiling tiles play the largest role in absorbing sound, says Niklas Moeller, vice president of K.R. Moeller Associates.

Moeller notes that studies show that acoustics in open-plenum buildings "are not great," and that while people prefer a green design, they complain about the noise factor. Building owners and operators have "a misperception that they can rely on one or two [of the ABCs], but you need all three," Moeller says. "Sound masking does not help with absorption. It controls background sound to help cover up noises in spaces that otherwise have library-like ambient conditions." Absorption, on the other hand, reduces volume level.

Green design isn't the only reason that office spaces are more acoustically challenging than in the past. Design strategies like lower partitions between workers, less space between workers and open work areas with conference tables, in addition to the elimination of the ceiling, all create a more noisy work environment.

Ceiling companies have developed products to help absorb sound in open-plenum offices. These products, which are available in a variety of shapes, may be suspended ceiling products designed to be installed over parts of a space or may be mounted directly on the deck.

A ceiling also plays a role in hiding speakers and wires. If there is no ceiling, the appearance of sound masking speakers and electronic components becomes a consideration.


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