By Mark Schmidt, AIA, CSI CCS, LEED AP BD+C, WELL AP, Specification Writer, and Mark Sweeney, AIA, NCARB, Chief Resource Architect

I have often been surprised at the thoughtlessness, (resulting in cruelty, quite unintentionally) of friends or of doctors who will hold a long conversation just in the room or passage adjoining to the room of the patient… …If he is an amiable patient, he will try to occupy his attention elsewhere and not to listen–and this makes matters worse–for the strain upon his attention and the effort he makes are so great that it is well if he is not worse for hours after. If it is a whispered conversation in the same room, then it is cruel; for it is impossible that the patient’s attention should not be involuntarily strained to hear … in one case death ensued. It is but fair to say that this death was attributed to fright. It was the result of a long whispered conversation, within sight of the patient, about an impending operation.

– Florence Nightingale, Notes on Nursing, 1860

When the Health Insurance Portability and Accountability Act (HIPAA) passed in 1996, more than a century after Florence Nightingale wrote about the importance of patient privacy, acoustical privacy regarding patient health information became a federal requirement. In October 2006, the Centers for Medicare and Medicaid Services (CMS) began asking discharged healthcare patients to complete the HCAHPS (Hospital Consumer Assessment of Healthcare Providers and Systems) survey. One of the eight “domains” that the HCAHPS survey measures is the quietness of the hospital environment.” Because HCAHPS scores are tied to reimbursement, healthcare providers now have a financial incentive for addressing sound in the design of their facilities.

An unwanted sound has negative consequences on comfort and wellbeing. It can increase stress and blood pressure, make pain relief more difficult, and inhibit the ability to heal. Ironically, the most fragile patients seem to end up closest to the nurse station, where the highest levels of day-to-day noise are generated. Healthcare designers need to consider how and where sound is generated and be aware of its impact on the spaces they are designing. Sound can originate both internally and externally. It can result from conversations, movement of objects, and even ground and air traffic. Sound can be managed by limiting the level of sound experienced in spaces and by making design decisions that minimize the impact of the resulting noise on patients and staff.

Sound Generation

As anyone who has visited hospitals knows, they are a vibrant and active environment. Between foot traffic, equipment, and voices, these sounds cumulatively become “noise.” A necessary evil of medical technology is “alarm fatigue” (both visual and audible). Caregivers can craft operational procedures to minimize noisy situations, but the physical design of the environment also impacts the extent to which environmental sound is addressed. Providing discreet “huddle” spaces for private medical conversations can be an effective way to provide for “semi-private” conversations. If space for dedicated rooms is not available, consider providing circulation spaces with alcoves that have sound-absorbent surfaces to minimize amplification.

If isolating patients from corridor “noise” is one’s goal, consider positioning the patient toilet rooms along the corridor instead of along the exterior wall. This arrangement has the added benefit of increasing the amount of daylight available to the patient room. If shared plumbing walls and shared headwalls are being justified as a way to save money, be sure to take acoustics into consideration. These back-to-back configurations will use less piping and conduit, but sealing up the resulting penetrations – to prevent sound transmission – will increase the “total cost.”

In addition to the physical arrangement of healthcare spaces, the walls of individual spaces can be designed to minimize the amount of external sound that intrudes into the spaces by using:

  • Wall assemblies designed to maximize their sound transmission class (STC).
  • Glazing assemblies designed to maximize their outdoor-indoor transmission class (OITC).

Note that Section 1207.2 of the International Building Code (IBC) – and at least one state licensing authority (Florida’s AHCA) – now have provisions to field-test the acoustical performance of these wall assemblies – and the IBC only allows a 5 decibel (dB) drop between lab- and field-based tests!

Doors and door openings continue to be a noise-control challenge since there is a conflict between the staff’s desire to see the patient and monitor equipment and patients and their families wanting quiet and privacy.

Given the ongoing pandemic, it might be worthwhile to re-examine the assumptions regarding open spaces like post-anesthesia care units (PACUs). Although patients are only in PACUs temporarily, could some of these spaces be enclosed to provide negative pressure environments – as well as quieter spaces?

Noise Management

Suspended acoustical ceilings were well-received when introduced in the 1960s partially because they could absorb more sound than plaster or gypsum board ceilings. Today they are the workhorses of healthcare sound control (with added performance characteristics like cleanability, aesthetics, and acoustical isolation). Feature #80 in the International WELL Building Institute’s (IWBI’s) WELL Building Standard (v1) suggests the following performance values in noise-reduction coefficients (NRCs) for ceilings (excluding lights, skylights, diffusers, beams, joists, and grilles):

  • NRC for the acoustical ceiling panels in open workspaces: 0.90 (90% absorption).
  • NRC for 50% of acoustical ceiling panels of conference and teleconference rooms: 0.80 (80% absorption).

Need more sound absorption? That same feature in the WELL Building Standard suggests an NRC of 0.80 (80% absorption) for at least 25% of the vertical surfaces. Although wrapped acoustical accent materials help, it is difficult to find appropriate finishes that both absorb sound and satisfy the cleanability standards of a healthcare facility.

Floor finishes like resilient tile and sheet floor coverings contribute little to the absorption of airborne sound, but at least one manufacturer has developed multilayer resilient floor coverings that measurably reduce foot- and wheel-generated “noise.”

Furnishing can help. Waiting rooms in healthcare facilities are populated by people who are neither patients nor healthcare staff. The atmosphere is intended to be quiet, but occasionally large groups of visitors can unintentionally be disrupting. The amount of noise waiting rooms generate should be minimized through the artful selection and arrangement of furnishings and fixtures. A good rule of thumb would be to cover at least 50% of the surface of furnishings with sound-absorbing materials. In addition, taller furnishings and fixtures could be provided to absorb sound traveling across these spaces. If possible, furnishings should also be movable to allow groupings to be flexible and help keep speech levels low due to the improved proximity of individuals.

Another tool available to designers to “sound-scape” spaces is sound masking. Rather than trying to “cancel” the unwanted sound, sound masking covers or shrouds it with low-level inoffensive sound approximately 5 or 6 decibels (dBs) above the objectionable noise. Historical “white noise” installations are now considered unnecessarily loud. Today the energy levels of sound masking are tailored to the frequencies of the unwanted sound present in the space. This tailored effect is referred to as “pink noise.” The best measure of a successful sound-masking installation is when the occupants don’t notice it unless it is turned off.

A “poor man’s white noise” is the strategy of fine-tuning the HVAC distribution system to simulate sound masking. To be successful, this solution needs to avoid becoming the unwanted noise itself. This can be optimized using a measurement known as noise criteria (NC), which is determined by measuring the sound pressure limits at specific octave bands between 63 and 8000 Hertz and then comparing the highest value in the resulting profile with pre-defined curves. The WELL Building Standard (v1) defines the following maximums for occupied areas:

  • NC in open office spaces and lobbies (similar to PACUs): 40.
  • NC in enclosed offices (similar to exam rooms): 35.
  • NC in conference rooms and breakout rooms (similar to treatment and operating rooms): 30 (25 recommended).
  • NC in teleconference rooms: 20.

Summary

Going forward, it is in everyone’s best interest for acoustics to be given full consideration in the design of healthcare facilities.