The Leaflet Article
Keeping Exams Confidential in Clinics
Sound Control is extremely important for confidentiality in clinics. Any audible transmission between exam rooms is a major HIPAA (Health Insurance Portability and Accountability Act) violation. Thus, special care is required to eliminate sound from migrating between spaces. The following are considerations to control sound within the clinic:
The first line of defense against sound transfer is the wall construction. Typically, walls are composed of 3 5/8-inch studs with 5/8-inch gypboard on both sides. And, the walls normally extend full height, from slab to structure above.
For exam room walls, sound attenuation material is highly recommended to be installed in the cavity, from the slab up to at least 24 inches above the ceiling. This dense fiber or spray-on foam material should have an STC rating of at least 50, and preferably 60 or greater. Several manufacturers of this material are Thermafiber, Owens Corning’s ‘Quietzone’ and Engineered System’s ‘Icynene’. This material must be noncombustible (with a fire rating, especially if used in a plenum) and should be specified for sound control, not thermal control.
Besides exam rooms, sound attenuation material should be installed in walls for procedure rooms, consult rooms, and offices. It may also be installed for staff break rooms and toilet rooms.
Typical ceilings in rooms is a basic acoustical lay-in tile system that is found in most commercial buildings. For healthcare facilities like clinics, specialized ceiling tiles are required. These tiles need to have a high NRC rating (preferably over.70) and be soil resistant, impact resistant, scratch resistant, and scrubable / washable. Armstrong and USG have ceiling tiles that meet these stringent healthcare environment requirements.
Depending on the wall construction, sound attenuation material can be placed above the lay-in ceiling. However, this is not ideal since over time, this material can be displaced due to maintenance access above the ceiling, which negates its effectiveness.
To control sound from the toilet room, it is suggested to install gypboard ‘hard’ ceilings in these small spaces.
If the mechanical system is fully ducted, both supply and return air, then no additional sound control may be required, depending on the nature of the clinic function.
However, most clinics are not required to have a double-ducted system. Usually just the supply air is ducted, and the return air is via an ‘open’ plenum, or no ductwork whatsoever for the return air. And, to allow the return air via a plenum to the air handling unit, the wall construction must have an ‘opening’.
Preferably, the wall construction extends from the slab to the structure above, with a ducted return air passage to the plenum space in the adjacent corridor.
However, if the slab to structure dimension is very high, then the wall construction may terminate just above the ceiling. This occurrence typically happens when a big box store is converted to a clinic, and the structural height is upwards of twenty (20) feet. Such wall height is very costly to extend from slab to structure. In this instance, sound attenuation placed on the lay-in ceiling might be the preferred cost-effective option.
Normally, an acoustical return sound boot (also called a ‘Z boot’) is installed in the return air grille in the exam room ceiling to reduce sound transmission via this ceiling opening. Although, as noted previously, sound attenuation material placed on a ceiling is likely to be displaced by maintenance at some future point, which will negate its effectiveness.
Another option is to install gypboard ceilings, although this is not desirable since it can cause reverberation within the exam.
Consultation with the clinical staff and the mechanical engineer on the wall construction is important during the design development phase so as to minimize sound transmission.
The room which contains the return air duct for the plenum system, where it connects to the air handling unit, should be sound-isolated due to the loud ‘whoosh’ noise that is created at this location. The door should be gasketed and the adjacent spaces may need to have either the walls extended to the structure or gypboard ceilings installed to minimize this disruptive sound.
Side Bar: STC versus NRC
When specifying sound control material, there are 2 ratings referenced: STC and NRC. STC is ‘sound transmission coefficient’ and measures how much sound that is transferred thru a wall. The higher the STC, the less sound is transferred. NRC is ‘noise reduction coefficient’ and measures sound absorption within a room. NRC ratings are from zero to 1. The higher the NRC, the better the sound absorption. NRC is usually for finish material such as lay-in ceilings and wall coverings.
Other Sound Control Considerations
For ‘double loaded’ corridors, where exam rooms are on both sides of the corridor, sound transfer will be a concern. Thus, to control verbal transmission from the exam rooms, do not place the exam room doors across from each other. Exam room doors should ‘alternate’ along the corridor.
Instead of 3 5/8 wall thickness, the width can be increased to 6 inches with the studs ‘staggered’ / offset. This though increases the cost as well as the square feet of a clinic. This is recommended for rooms that contain audio booths for hearing exams.
Electrical outlets should not be installed ‘back-to-back’. Back-to-back outlets allow sound to transfer between rooms.
Resilient channels can be installed between the stud and gypboard. This method is especially recommended for very sound sensitive spaces such as otolaryngology (hearing) exams and sound booths.
Air compressor rooms in dental clinics need special sound control design. Not only sound attenuation material in the walls, but also recommended 6-inch staggered stud walls with gypboard ceiling. The door to this room should be gasketed, and if possible, a vestibule should be constructed to provide a double door ‘air lock’ separation between the dental area and this very loud noise producing space.
Likewise, where an interior electrical transformer is located should be sound isolated since these units can make a loud humming noise.
‘White noise’, or ‘sound masking’, is sometimes used. ‘White noise / sound masking’ is created by an audio system usually mounted on a ceiling. The ‘noise’ sounds like water running or a low hush-type sound. The audio level can be adjusted per staff preference. Many open office layouts employ this system and it is not very detectable but does help in minimizing audio transmission. Cambridge Sound Management is one suggested vendor for this type of sound control.
Without proper sound control, patients and staff both will dissatisfied and the clinic will be an unsuccessful healing environment till this disruptive issue is adequately resolved to all concerned.
Steve Wiser, FAIA, has over 40 years and $2 billion dollars of healthcare design experience. Information on his new book, “Clinic Design & Construction Guidebook: Improving Patient Care by Improving Clinic Projects” can be found by clicking on www.WiserDesigns.com