|Each year, J.D. Power conducts its North American Hotel Guest Satisfaction Index Study, seeking the opinions of approximately 50-60,000 travelers. Noise has regularly ranked first in the list of complaints, industry wide. It irritates guests during the day and continues to affect their ability to sleep long after they have adjusted to their new surroundings.
The financial impact of this problem can be substantial. Dissatisfied guests are less likely to return to a property and more inclined to voice their frustration to others and post negative reviews online. As a result, the hotel’s reputation can suffer. In many cases, there are also direct costs associated with appeasing unhappy guests, such as offering room rebates and discounted services.
Clearly, noise is a serious issue, but there are solutions. Acoustic professionals usually take a three-pronged approach to this problem, implementing methods to absorb, block, and cover noise. Because achieving the desired results requires the balanced application of all three strategies, they are often collectively referred to as the ABC Rule. In order to create a comfortable and relaxing environment, this rule should be applied to both guestrooms and corridors.
Absorptive materials reduce the volume of noises reflected back into a space, the length of time noise lasts, and the distance over which it travels.
The most significant source of absorption in many facilities is the ceiling. Though guestrooms usually feature hard ceilings, an absorptive ceiling should be used in corridors. Properties may also add absorptive panels to corridor walls. Today, many attractive options are available, even ones featuring custom artwork. Soft furnishings can also be used to absorb noise produced within the room itself.
Installing carpeting in both corridors and guestrooms will help to lessen impact noise, such as footfall. As per the Uniform Building Code (UBC), hotels should use floor and ceiling assemblies with a minimum Impact Isolation Class (IIC) rating of 50.
Blocking noise is achieved using windows, walls, doors, and other physical structures. A partition’s Sound Transmission Class (STC) rating indicates how well it will attenuate airborne sound—the higher the number, the better the performance.
Walls and floor/ceiling assemblies should meet a minimum of STC 50, as required by the UBC for Residential (Group R). For further sound blocking, it is recommended to use STC 65 to 70 walls. Resilient channel, strips of metal that space the drywall away from the framing, can improve a wall’s isolation, but its effectiveness will be greatly reduced if artwork or headboards are mounted against it.
Noise not only transfers between guestrooms, but also from one guestroom out into the corridor and then back into adjacent guestrooms. Therefore, properties should also ensure sufficient corridor-door isolation. The STC rating of interior doors should be 26 or higher.
However, blocking involves more than installing barriers. Selecting materials with high STC ratings will be meaningless unless all gaps are also addressed. For example, avoid installing outlets, light switches and telephone jacks back-to-back. Install drop seals and jamb gaskets under and around doors, and ensure these items are well maintained.
Since the majority of exterior noise (e.g. car, train or airplane traffic) is transmitted through windows and Wall Packaged Terminal Air Conditioner (PTAC) units, it is advisable to ensure a high level of acoustic performance from these components. In the case of windows, strategies such as providing an exterior of thermal double glazing and an interior sull sash of heavy glass are effective.
Blocking is also achieved through an appropriate layout. Locate noisy equipment (e.g. elevators, vending and ice machines) away from guestrooms. Floor-to-floor sound transmission can be mitigated by positioning restrooms, for example, in the same area on every floor. If any noisy equipment or activities are to be located directly above a guestroom, use special double floor and room-within-room construction to contain the noise.
We have all heard the old adage “silence is golden,” but there is a comfort zone for the volume of sound and it is actually not zero. For this reason, the final step of the ABC Rule involves ensuring that the background sound level in the space is sufficient to cover speech and noise.
Even when properties wisely invest in construction to mitigate noise transmission, there are economic limits to what can be done – particularly in retrofit situations – and noise can remain an irritant because, while absorption and blocking reduce volume peaks, they also reduce overall background sound levels. The lower the background sound level, the louder other noises seem to occupants and the more disruptive they are to sleep.
Guests often try to use the hotel’s HVAC system to raise the background sound level in their room because they intuitively know that it will cover up at least some unwanted noise. While these systems provide a degree of masking effect, they are not designed for this purpose. And because they cycle on and off, such mechanical noises are unreliable and can grow irritating. Furthermore, when used excessively, energy consumption and maintenance costs increase.
A commercial-grade sound masking system can be used to properly replenish and control the background sound level in guestrooms. This technology uses a loudspeaker to introduce a comfortable, engineered sound into the room. Guests can adjust the masking’s volume according to preference – just as they would the temperature and lighting – covering or reducing the noise from adjoining rooms, corridors, elevators, mechanical systems, ice machines, traffic and bars.
Niklas Moeller, MBA, is vice-president of K.R. Moeller Associates Ltd., a global developer and manufacturer of sound masking system, LogiSon Acoustic Network. He also writes a weekly acoustics blog called “UnMasked – an inside look at acoustics” at www.soundmaskingblog.com.