-by Julie Fischer INCE, LEED AP BD+C
“Unnecessary noise, then, is the most cruel absence of care which can be inflicted either on the sick or the well” — Florence Nightingale, Notes on Nursing, 1859
Anyone that has stayed in a hospital knows that the above statement is completely accurate. You aren’t feeling well and may be anxious and afraid. All you want to do is get a good night’s rest because things will surely look better in the morning. Unfortunately, all you can do is lie awake and listen to all the sounds in the hospital. Equipment beeps, the HVAC system turns on and off, and the patient in the room next door is having a worse night than you. Proper design of the environment in which healthcare takes place can have a significant impact on the overall acoustical environment to which a patient is exposed. But how do we define what a proper environment is and what are some of the pitfalls that even the most careful design team could fall into?
When considering acoustics in a healthcare facility, there are two main issues that need to be addressed:
- How do we provide a comfortable environment for patients to recover from injuries and illness by reducing the impact of surrounding noises?
- How do we provide an appropriate environment for doctors, nurses, and patients to communicate clearly with each other so that verbal communication is understood and directions are followed?
The primary aspects of acoustics that influence the overall soundscape of a patient room are sound isolation and background noise. The best way to control noise in a patient room is to make sure that it does not get into the space in the first place. Solutions such as upgraded partition constructions, door seals, and space planning (i.e., locating noisier areas such as nursing stations away from quieter areas such as patient rooms) are all potential solutions. Proper design of HVAC ductwork—including maintaining appropriate air speed velocities in ducts and at diffusers, as well as providing sound attenuators in appropriate locations—helps to maintain a quiet and high-quality acoustical environment.
When a design team starts to think about using the space to promote quality verbal communication, the types of acoustical finishes provided in the space start to play a significant role. While acoustically absorptive finishes are somewhat at odds with the needs of a healthcare space (porous materials can harbor bacteria), when used appropriately they can greatly improve the overall environment. For example, acoustically absorptive ceilings can aid in reducing overall noise build up within occupied spaces, however the treatment should be kept away from areas where it might get damaged or dirty.
There are a number of standards and guidelines that can inform the design of a healthcare facility. These include the following:
- World Health Organization (WHO): The WHO suggests that indoor sound levels for patient rooms should not exceed 30 dBA at night. During the day, noise levels in patient rooms should not exceed 35 dBA. As a point of reference, a study done by Johns Hopkins University in 2005 found that noise levels in hospitals rose from 57 dBA in 1960 to 72 dBA in 2005 during the day and from 42 dBA in 1960 to 60 dBA in 2005 at night. Even in 1960, we were not able to achieve the recommended background noise criteria and the overall sound levels are only getting louder.
- Facilities Guidelines Institute for the Design and Construction of Hospitals (FGI): This document and its corresponding versions for Residential Health, Care & Support Facilities and Outpatient Facilities comment on a wide range of acoustical topics. These include guidelines for partition ratings and construction, interior finishes recommendations, appropriate background noise levels for various spaces and design of building facades to mitigate external equipment noise.
- LEED for Healthcare v4.1: The credits for acoustics reference the guidelines set forth in the FGI documents by using them as a baseline for sound isolation and background noise. An additional point can be achieved by complying with the FGI guidelines for interior finishes and exterior noise control.
The guidelines above lay out a solid foundation for the construction of healthcare facilities. They help to define an appropriate baseline for a comfortable acoustical environment. But guidelines cannot capture the nuances of each individual space. So, what are some of the pitfalls that can trip up even the most cautious design team?
- Partition stud gauge and spacing: A typical STC 45 rated partition is generally constructed as follows:
- 1/2” or 5/8” drywall
- 3 5/8” stud filled with batt insulation
- 1/2” or 5/8” drywall
Partition is constructed full height, structural slab to structural slab.
This is a commonly used and understood construction, however; the STC 45 rating associated with it is only applicable to 25-gauge studs located 24” on center. If the stud gauge is stiffer (i.e., 16- or 20-gauge studs) or the spacing is decreased down to 16” on center, the tested STC rating of the partition drastically decreases. This decrease can be as much as 10 STC points. When considering the design of a standard, spec office building, this may not be a concern but if you are beholden to one of the above listed set of guidelines, this deviation becomes much more critical. To meet the FGI guidelines, extra layers of drywall or resilient clip solutions may be necessary, adding cost to the project. Early establishment of the type and spacing of the partition studs and planning to use the optimal gauge can help with budget concerns as the project moves through the design phases.
- Door conditions: Similar to partition constructions, door constructions can play a significant role in the overall separation of two spaces. Many spaces in healthcare facilities prioritize quick access over acoustical separation. An example of this would be operating rooms, which often have swing doors on the entrances to provide easy access to gurneys. However, there are some spaces, such as counseling rooms or even some patient rooms, where acoustical privacy takes precedence. In those cases, solid core or insulated doors with frames should be implemented. Adjustable neoprene and automatic drop seals also aid in maintaining separation. These can be selected to meet ADA requirements.
- Equipment noise: There are many pieces of equipment that go beep in the night. This can disrupt sleep, cause stress, and lead to slower recovery times. Excessive use of audible signals can also cause fatigue among caregivers leading to slower response times. Some of the sounds implemented by these devices are medically necessary but, during the design phases, each noise emitting device should be evaluated to determine if the signal can be reduced or eliminated so as not to flood the environment with unnecessary sound. Some potential solutions include:
- Intelligent nurse call systems
- Alternatives to overhead paging including patient tracking, beepers, and vibrating pagers
- Locating nurse stations away from the patients’ rooms and potentially erecting transparent barriers or use upgraded acoustical finishes between the two spaces that allow for visibility but help to block noise.
The above are just a few examples of areas where additional consideration early in a project could lead to a better performing, more comfortable facility for patients and staff. Other potential areas of concern with regards to acoustics could include medical helicopter flight paths, vibration criteria for sensitive medical equipment, etc.
A successful healthcare project is one where the overall environment supports both healing and communication. The achievement of this goal relies on adherence to well established guidelines, such as those noted in the FGI guidelines, as well as a targeted study of the individual aspects of the project that may not be spelled out within those guidelines. Through good design, the building will be not only a structure where healing takes place, but a positive influence improving the healing outcomes of countless patients.
Julie Fischer INCE, LEED AP BD+C is a Principal Consultant in the Washington DC office of NV5 Engineering & Technology (formerly Sextant Group). Julie directs our acoustics practice and is a leader and mentor for our team of acoustical consultants across North America.
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