ASHRAE LV-11-C030-2011 Hospital Noise and Occupant Response.pdf

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1、Erica Ryherd is an assistant professor in the Woodruff School of Mechanical Engineering and adjunct to the College of Architecture, Georgia Institute of Technology, Atlanta, GA. Selen Okcu is a PhD student in the College of Architecture, Georgia Institute of Technology, Altanta, GA. Timothy Hsu is a

2、 PhD student in the Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA. Arun Mahapatra is a Masters student in the Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA. Hospital Noise and Occupant Response Erica Ryherd, PhD, LEE

3、D AP Selen Okcu Timothy Hsu ASHRAE Member Student Member ASHRAE Student Member ASHRAE Arun Mahapatra Student ABSTRACT Hospitals should be conducive to patient recovery and safety as well as employee health and productivity. A variety of diverse noise sources populate hospitals such as HVAC systems,

4、occupant sounds, alarms, and medical equipment. There is strong and growing evidence of the negative impacts of a poor hospital acoustic environment. For example, patient sleep disruption, cardiovascular arousal, increased incidence of rehospitalization, and extended hospital stay have been linked t

5、o hospital acoustics. There is also evidence that staff mental efficiency, short-term memory, stress, burn-out, and hearing loss are related to the acoustic environment. The Hospital Acoustics Research Team (HART) is a unique collaboration of specialists in engineering, architecture, psychology, med

6、icine, and nursing that is working to evaluate the modern hospital acoustic environment and the associated psycho-physiological responses of occupants. Case studies and findings from this body of work will be discussed. The results are advancing the understanding how various aspects of the acoustic

7、environment impact occupants, how to best measure and quantify these aspects, and how to improve the hospital acoustic environment to make hospitals healthier for occupants. INTRODUCTION A soundscape is defined as “an atmosphere or environment created by or with sound 1.” The topic of the acoustic e

8、nvironment, or soundscape, in hospitals has been attracting a lot of attention in recent years. The reasons are multifold. To begin with, the soundscape in hospitals is unique and complex: a variety of diverse mechanical noise sources populate hospitals in addition to the heating, ventilating, and a

9、ir-conditioning (HVAC) systems and other traditional building services. A few examples found in hospitals are alarms, medical equipment such as respirators, alternating air pressure mattresses on beds, paging and call systems, service carts, ice machines, medication dispensing systems, automatic doo

10、r closers, automatic hand sanitizers or paper towel dispensers, and cleaning equipment. In addition, hospitals are active places; conversations, footfall, activity noise, and patient bodily sounds are just a few of the assorted human sounds present. Additionally, there is growing evidence of the neg

11、ative impacts of a poor soundscape on occupants, as discussed below. The Hospital Acoustics Research Team (HART) is a collaboration of specialists in engineering, architecture, psychology, medicine, and nursing from various universities, medical facilities, and industry. HART has been actively condu

12、cting research to evaluate the modern hospital soundscape and the associated psycho-physiological responses of occupants. Results from HART research work are being used to refine methods of quantifying hospital soundscapes and LV-11-C030248 ASHRAE Transactions2011. American Society of Heating, Refri

13、gerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions, Volume 117, Part 1. For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAES prior written permission.determine how

14、currently challenging soundscapes might be enhanced. Results from recent HART studies are highlighted in this paper, with a focus on data collected by the authors. BACKGROUND The soundscape in hospitals has long been a source of complaints among hospital staff, patients, and visitors 1,3. Clearly, h

15、ospitals should be conducive to patient rest and healing. Unfortunately, some of the findings are that noise in hospitals can disrupt patient sleep 4-10, elicit cardiovascular arousal 11,12, extend hospital stay 12, and relate to increased dosages of pain medication 13. Further, increased sound abso

16、rption has been linked to improved sleep 15, a decreased incidence of re-hospitalization 16, and a reduction of cardiovascular arousals 16. Decreased healing is another potential concern as animal testing has revealed that wound healing may be slowed 17,18. Hospitals should also promote staff health

17、 and task performance, yet there are much fewer studies related to this topic. Some of the findings show that overall noise levels may contribute to staff burnout 19, stress 20-22, and hearing loss in certain circumstances 23. Acoustic interventions, such as increased sound absorption, have been cor

18、related with improvement in staff psychosocial environment 24 and perception of noise 25,26. Although speech interference and increased medical errors are two additional, potentially hazardous effects of hospital acoustics that have been proposed, these effects have not been thoroughly investigated

19、3,27. Initial evidence shows that one in four voluntarily reported medication errors involved confusion of drug names, with both spelling and sound similarity increasing the potential for false recognition errors 28. Despite the growing evidence of the potentially negative impacts of a poor hospital

20、 soundscape, there are many remaining questions. Many of the previous publications are lacking in details regarding the measurement methodologies, architectural finishes and layouts, mechanical systems design, occupant activities, and other characteristics of spaces which impact the acoustics. Furth

21、er, the majority of previous work has focused primarily on overall background noise levels. Information about spectral content, fluctuations over time, and other more detailed properties of background noise is typically lacking. Very little work has been done on other properties of the room acoustic

22、 environment, such as reverberation, speech intelligibility, etc. Finally, although it is generally accepted that there are relationships between the acoustic environment and occupant response, the exact nature of these relationship needs to be defined in order to understand how to craft hospital so

23、undscapes that are most conducive to the health and well-being of staff, patients, and visitors. Of particular interest to ASHRAE is the contribution of HVAC systems in hospitals to the background noise levels. As such, the topic of background noise and highlights of occupant response will be the pr

24、imary focus of this paper. Multiple studies will be plotted and analyzed together with an aim of presenting the overall picture and drawing some general conclusions from recent research. Case studies and findings from literature published since 2005 are synthesized in this paper, along with new find

25、ings not previously published. Historical Noise Levels: 1960 2010 This section will discuss results from two analyses: a) a recent landmark study by Busch-Vishniac et al. covering historical data up to the year 2005 3; and b) data from study (a) combined with new data collected by HART since 2005 20

26、,26,29-34. The Busch-Vishniac et al. study showed that noise levels have been rising over the last 40 years 3. More specifically, researchers found that both the average day- and nighttime equivalent sound pressure levels (Leq) had risen by significant amounts. Since 2005, the area of hospital acous

27、tics research has grown and expanded considerably. Figure 1 shows historical data from study (a) published by Busch-Vishniac et al., with the plots expanded to include HART data collected since 2005 (b). In all, 36 daytime and 42 nighttime results are shown in Figure 1 and include a variety of types

28、 of hospitals and units located throughout the world. Additional details about the data compilation techniques used in generating Figure 1 can be found in Busch-Vishniac et al. 2005 3. A few interesting points are observable from the Figure 1 data. In the original Busch-Vishniac et al. study the aut

29、hors point out that all of the published results from 1960 2005 lack compliance with various building standards and guidelines 2011 ASHRAE 2493. For example, the World Health Organization (WHO) guidelines recommend a maximum Leq of 35 dB(A) in patient treatment and observation rooms and 30 dB(A) in

30、ward rooms 27. The 2005 2010 hospitals plotted in Figure 1 also far exceed the WHO recommended levels. One important item to note is that the data shown in Figure 1 are typically occupied background noise levels. A linear trendline indicates that daytime levels have increased by 0.2 dB per year on a

31、verage. This increase is slightly lower than the Busch-Vishniac et al. published increase of 0.38 dB per year 3. The increase in nighttime levels, however, is quite consistent with the Busch-Vishniac et al. published results 3, with sound levels increasing on average 0.4 dB per year. Although not sh

32、own in Figure 1, another interesting result was the range of Leq reportedthe highest and lowest Leq values measured in each study. The results are summarized in Table 1. Prior to 2005, many of the studies reported single, averaged Leq values with no range. Table 1 shows results from only those studi

33、es that did report a range. The maximum range reported by any one study was 12 to 14 dB(A) depending on whether it was day or night. The average reported range was 8 dB(A). This means that the lowest Leq level was on average 8 dB(A) below the highest Leq level measured. In the more recent data, a mu

34、ch greater range of Leqs is reported as shown in Table 1. The average reported range was 27 to 28 dB(A). The large differences in range pre- and post-2005 are likely due to several factors. One may be that hospitals have simply become more active over the years and thus the background noise has beco

35、me more fluctuating. An additional, very likely contributing factor is that the more recent data have been collected using a more rigorous methodology than some of the earlier studies, resulting in more data points and a greater range of Leq values. For example, the sound level meters used in earlie

36、r studies had less capacity to measure for long periods of time. Additionally, in the recent studies data are collected in many locations within individual units (e.g., patient rooms, nurse stations, corridors). Data is also collected using relatively short averaging intervals (typically 1 minute),

37、whereas some of the previous studies used much longer averaging intervals. a) b) Figure 1 A-weighted equivalent sound pressure levels (Leq) as a function of year of publication during (a) daytime hours, and (b) nighttime hours. Portions reproduced from 3 with permission. Table 1. Ranges of Levels Pu

38、blished from (1960 2004) versus from (2005 2010). Daytime or Nighttime Publication or Measurement Date Max Range of Leq Published in dB(A) Average Range of Leq Published in dB(A) Daytime 1960 2004 14 8 Daytime 2005 2010 32 27 Nighttime 1960 2004 12 8 Nighttime 2005 2010 33 28 250 ASHRAE Transactions

39、RECENT HOSPITAL SOUNDSCAPE RESEARCH The remainder of this paper presents highlights of data collected by the authors since 2005. Four types of units are included: Neurological Intensive Care Units (Neuro ICUs), Medical-Surgical Intensive Care Units (MedSurg ICUs), Emergency Departments, and a Cancer

40、 Unit. Additional details about the units are shown in Table 2 below. The various units are located in hospitals in the U.S. and Sweden. All of the units had linoleum tile flooring, gypsum board walls, and lay-in acoustic tile ceilings, with the exception of the Emergency Departments which had gypsu

41、m board ceilings. In each type of unit, methodologies were as similar as possible. However, some differences existed due to site access and preferences of the hospital administrators and unit staff. The results shown for each unit represent an average across multiple locations in each unit. In all u

42、nits, unoccupied measurements were made in patient rooms. The length of the unoccupied measurements varied from 45 minutes to 24 hours depending on access, with most lasting 45 60 minutes and taking place during daytime hours (7 am 7 pm). The occupied areas measured in each unit varied as shown in T

43、able 2. The length of the occupied measurements were typically 24 hours in patient rooms and nurse stations, and 15 or 30 minutes in staff work areas, ambulance bays, triage, waiting areas, and corridors. For all measurements, sound data was collected using one-minute averaging intervals and a fast

44、response time for equivalent, maximum, and minimum levels. Larson Davis type 824 sound level meters and Larson Davis Utility Software were used for data collected in US hospitals. Brel and Kjr (B e.g., ability to cope with other noise sources may be lessened if the HVAC noise is problematic. There i

45、s also a great deal of effort underway to update hospital acoustic guidelines using recent research evidence. HART aims to provide evidence to help support new guidelines, by clarifying the relationship between the hospital soundscape and occupant response, identifying and evaluating new acoustic in

46、terventions, and transferring knowledge back to the engineering, architecture, and medical communities. ACKNOWLEDGMENTS This work has been supported by the Acoustical Society of America, the Swedish Council for Working Life and Social Research, the Health Systems Institute, the Boston Society of Arc

47、hitects, and Johns Hopkins Hospital. We are indebted to the patients, staff, and administrators at Emory University Hospital, Midtown Hospital, Johns Hopkins Hospital, Sahlgrenska University Hospital, and Bors Hospital. We greatly appreciate the contributions of Craig Zimring and Joe McKenzie (Georg

48、ia Institute of Technology); James West and Colin Barnhill (Johns Hopkins University); Ilene Busch-Vishniac (McMaster University); Jeremy Ackerman and Owen Samuels (Emory University Hospital); Kerstin Persson Waye, Berit Lindahl, Ingegerd Bergbom and Lotta Johansson (Gothenburg University); and Mari

49、e Swisher (Johns Hopkins Hospital). REFERENCES 1. 2010. The American Heritage Dictionary of the English Language. 4thEd, Houghton Mifflin Harcourt Publishing Company. 2. Baker, C. 1984. Sensory overload and noise in the ICU: Sources of environmental stress. Crit. Care Quarterly, 6: 66-79. 3. Busch-Vishniac, I.J. West, J., Barnhill, C., Hunter, T., Orellana, D. and Chivukula, R. 2005. Noise levels in Johns Hopkins Hospital. J. Acoust. Soc. Am., 118: 3629-3645. 4. Wil