The Effects of Material Selections on Noise Levels in Two Patient Care Units
As one of the country’s largest hospital construction projects, it has already captured the attention of healthcare professionals worldwide for its use of nature, light, and space—all designed to speed healing.
The new facility will provide expanded trauma and emergency services, heart surgery, neurosurgery, and vascular services in a structure designed with the flexibility to accommodate emerging technologies.
PMC West’s unique design will meld high-tech elements within a healing environment of gardens, terraces, and outdoor balconies. Waiting areas will have access to fresh air and two-story courtyards on each floor that will bring the calming power of nature to patients, families, and staff.
Natural light will permeate the structure; even the traditionally stressful environments of the interventional platform, trauma, and emergency will feature skylights and courtyards, creating a brighter, greener atmosphere. A quieter environment was adopted as one of the key goals for the new hospital.
Noise in hospitals has been growing for the past several decades, and after six years of development, the 2010 Guidelines for the Design and Construction of Healthcare Facilities included a new section on acoustic design. The high ambient noise levels, and specifically the peak noise levels in hospitals, have serious impacts on both patient and staff outcomes ranging from sleep loss and elevated blood pressure among patients to emotional exhaustion and burnout among staff.
The negative impact of noise can also impede effective communication between caregivers, patient confidentiality, and satisfaction.
Although the selection of building materials can have an influence on noise levels, a competing consideration was the ease of rolling patients and carts over different types of flooring. PPH was particularly interested in learning the impacts of hard surface flooring on noise levels and whether any additional noise could be mitigated by the application of high-performance acoustical ceiling tile.
A study was designed to evaluate the impact of the choices for flooring and ceiling tile on the activity noise levels within the corridors and nurses’ stations so that better-informed decisions can be made about interior finishes in new construction projects and ongoing refurbishment projects.
Two types of research tools were used, including both the objective measurement of sound level and the subjective studies of perceptions of noise before and after the changes.
The study was conducted on two inpatient nursing units (T6: Telem and T8: Med/Surg) at the current Palomar Medical Center. Prior to the study, both units had carpeted corridors and standard acoustical ceiling tile. As part of the study, new hard surface flooring (a resilient tile) was installed in T6: Telem.
Subsequently, high-performance acoustical ceiling tile (a mineral fiber tile) was installed on this unit. The other nursing unit, T8: Med/Surg, received new carpet tiles (a low, dense, loop construction designed for heavy traffic areas, with a nylon face that has a pile height of 0.187 inches, or 4.7 mm, and 9.4 stitches per inch).
The environmental interventions/conditions at each location and study phase are summarized in Figure 1 (see Image Gallery).
With respect to the objective measurements, sound monitors were located at four measurement points on each floor (the elevator lobby, the central nurses’ station, just outside a centrally located patient room, and just outside a patient room at the far end of the floor), and the acoustic measurements were conducted in three phases, as shown in Table 1.
In addition to the sound level measurements, both a patient survey and a staff survey were used to collect relevant subjective data. The surveys, which were adapted from prior Pebble Projects related to acoustics, consisted of 14 to 19 questions pertaining to noise sources inside and outside the room.
Noise measurements (dB data)
Since the actual noise sources vary over time, we reviewed statistics to evaluate whether the number and type of noise incidences are more or less the same over a long enough period of time (five to seven days), such that comparison data are meaningful.
The noise readings obtained from the sound level monitors were analyzed to determine if adding hard floors increased or decreased the mean, maximum, and/or median noise levels. Measured noise levels increased significantly when the existing carpet was replaced with resilient floor tile (hard surface) on T6: Telem.
However, when high-performance acoustical ceiling tiles were installed, the difference persisted only for the maximum noise levels in the elevator lobby, which exhibited an unusually high level of activity on only two days of the entire monitor cycle, and likely had more to do with special causes than architectural effects.
This direct comparison of the hard flooring and high-performance acoustical ceiling (T6 Phase Three) to the new carpet and standard ceiling (T8 Phase Two) indicates lower noise levels with the first combination; however, this conclusion is made with caution due to uncertainty that the noise sources are equivalent between the two floors.
The direct comparison of the new hard floor and new high-performance acoustical ceiling (T6 Phase Three) to the old carpet and standard ceiling (T6 Phase One) shows no perceptible difference in noise level. Given these two sets of noise measurements, it can be concluded that the combination of hard flooring and high-performance acoustical ceiling will perform equal or slightly better than the current carpet with standard acoustical ceilings.
Only one noise source addressed by the survey showed a statistically significant difference between the two units.
For the question pertaining to hallway noise from moving equipment, both the mean score and the percentage of patients indicating they were “Not at all” bothered indicated that the T6: Telem was noisier during Phase III than T8: Med/Surg was during Phase II. (Phase I (baseline) responses for this question were not statistically significantly different between the T6: Telem and T8: Med/Surg, so the T6: Telem Phase III and T8: Med/Surg Phase II difference is not a carryover from differences in the two floors’ baseline noise levels.)
From a staff perspective, prior to the interventions, there were significant differences between the units for five types of noise: talking in the hallway; doors opening, closing, and slamming; and alarms on equipment being more bothersome on T6: Telem.
On the other hand, intercom and call lights, and squeaking parts on beds, wheelchairs, stretchers, or carts were seen as not at all or only somewhat bothersome on T8: Med/Surg.
Following the interventions of both the hard-surface flooring and high-performance ceiling tile on T6 and the new carpet on T8, there was only one significant difference in noise source (doors opening, closing, and slamming), implying that there were several perceived improvements from a staff perspective on T6: Telem relative to T8: Med/Surg.
This is correlated to findings that staff on T6: Telem indicated the calming atmosphere was “better” than prior to the interventions.
The post-intervention survey that considered multiple aspects of the design interventions indicates that despite improvements in how bothersome several noise sources were on the unit, two noise categories (beds, wheelchairs, and stretchers; and carts) were still perceived as &ld
quo;worse” with a hard-surface floor relative to carpet.
As two areas with a direct relationship to the floor, this makes intuitive sense, whereas some of the other noises, (such as alarms) could be better absorbed by the high-performance ceiling tile.
The noise data suggest that hard floors with acoustical grade ceiling tile are comparable to carpeted floors with standard (existing) ceiling tile. The only significant difference suggests that hard floors with acoustical grade ceiling tiles may be more effective at reducing maximum noise levels than is carpeting.
An additional phase of the study was not completed (evaluating high-performance ceiling tile and carpet), but based on the results collected, it is hypothesized that additional acoustical improvements would be gained through this untested combination.
Additionally, comparing T6: Telem Phase Three to T8: Med/Surg Phase Two, the patient survey data suggest that hard floors with acoustical grade ceiling tile are comparable to carpeted floors with standard (existing) ceiling tiles when assessing patient perceptions.
Staff perceptions are consistent with patient responses suggesting that the acoustical grade ceiling tile improves the performance of a hard surface floor to that of carpet from an acoustical perspective.
Other issues related to perceptions of safety (slips and falls) were perceived as better with a carpeted floor. Ease of maintenance, however, was perceived as better with a hard surface floor. HCD
Edwin Bradley, PPH Volunteer; Dan Farrow, PPH Facilities; Kathy Mendez, RN, PPH Nursing; Deborah Hodges, RN, PPH Nursing; Robert Alvarado, C.M. Salter Consultants (acoustician); Steve Fox, PPH Facilities. Statistical analysis was conducted by Joseph Szmerekovsky, PhD, North Dakota State University College of Business.
Carrie Frederick is Director, Performance Excellence at Palomar Pomerado Health. Ken Roy is Senior Principal Research Scientist at Armstrong World Industries. Ellen Taylor is Director of Pebble Projects for The Center for Health Design. Amy Keller is a former Research Associate and Pebble Design Strategist with The Center for Health Design and is currently with SOM Architects. Marcia Jackson is Director, Facilities Planning & Transformation at Palomar Pomerado Health. Ridley Kinsey is former Vice President, Sales, Healthcare at Tandus, is currently on the Advisory Board of the AAHID, and has worked with The Center for Health Design on several research initiatives. For more information, please visit The Center for Health design at www.healthdesign.org or Palomar Pomerado Health at www.pph.org.