Noise solutions that work for other industries

Sound masking technology provides precise control over the background level
Friday, September 21, 2012
By Niklas Moeller

Noise complaints usually stem from neighbours, hallway activity, exterior traffic, mechanical systems and plumbing. The impact can be significant, ranging from irritation to recurring sleep disruption. Solutions are often difficult and expensive to implement, and involve multiple parties.

Of course, noise is not unique to condos. Designers and owners of other types of buildings have dealt with the same challenges for decades. As a result, there is much to learn from their experiences.

Acoustic problems are not necessarily caused by poor insulation but rather by a low level of interior ambient sound, which allows noises to be more easily heard and from much further away. Commercial office designers were the first to pick up on this problem and to adopt a solution for it: sound masking. This technology distributes an engineered sound throughout a space, providing precise control over the background level. Though most people compare the sound to softly blowing air, it is designed to mask human speech and also covers up or reduces the impact of other types of noises.

Using sound masking in private offices is reasonably analogous to a condo application, though office walls typically reduce less sound than the demising walls between condo units. Perhaps a closer comparison can be made with hotel guestrooms.

As in guestrooms, condo noises are typically not very loud. Rather, occupants perceive the noises as loud because of the difference between their volume and the background sound level in the space. For example, the ambient level in guestrooms is usually between 28 and 34 decibels (dBA) when the HVAC is off. Though intermittent noises often measure less than 40 dBA, they are nonetheless disruptive because they are easily heard in these otherwise silent spaces. Hoteliers are also turning to sound masking technology to provide a more effective background sound level in guestrooms.

Research of the health care industry has found that intermittent noises disrupt sleep when they exceed the background sound level by a certain number of decibels. People sleep better in a masked space than in one with a low ambient level punctuated by intermittent noises because masking reduces the amount of volume change between the baseline level and these sporadic sounds. This fact has also been demonstrated with regards to traffic noise in a residential bedroom. The Facility Guidelines Institute’s guidelines for the design and construction of health care facilities now recommend sound masking be included in patient rooms.

In the office, hotel and health care sectors, occupants have appreciated being given precise control over ambient sound levels in their space, the same way they can control lighting and temperature. Not only do personal preferences differ but the level of masking volume can fluctuate throughout the day and night. Providing occupants with the ability to adjust the volume allows them to maintain a balance between effectiveness and comfort.

These industries have demonstrated that, unlike other acoustical interventions such as modifying the exterior building shell or windows, sound masking can be easily installed in an existing space with minimal cost and disruption. Also, because it works at the ear of the listener, it can be independently applied by an occupant rather than by treating a neighbouring unit.

Niklas Moeller is vice-president of K.R. Moeller Associates Ltd., a Burlington, Ont., based manufacturer of the first networked sound masking system, LogiSon Acoustic Network.

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