NOISE AND ACOUSTICS FORHEALTHCARE DESIGNBy Darron Chin-Quee, M.B.A., P.Eng.

CONSULTING ENGINEERS & SCIENTISTS

INTRODUCTION

Noise and acoustical challenges in healthcare facilitydesign range from meeting legislated requirements tothe primary mandate of creating environmentscompatible with healing. Regulations such as the U.S.Health Insurance Portability and Accountability Act(HIPAA) require confidentiality of patient information.It is also desirable to promote patient wellness bycreating a restful environment. These concernsencompass noise and acoustical considerations such asspeech privacy, sound isolation and noise controlwithin and external to the building.

Compounding the design complexity is the large variety of spaces,each with different noise sensitivities and noise sources (ranging fromcrying babies to rooftop mechanical units).

Stakeholders

Facility stakeholders (i.e., patients, staff, and funding agencies)benefit from appropriate design for noise and acoustics. The Staffexperiences less stress and strain, potentially reducing staff turnoverrates (Blomkvist et al., 2004). Patients have less stress and sleepbetter, which can contribute to lower re-hospitalization rates andimproved patient satisfaction. Noise control is an essentialcomponent of patient-centered healing (Urlich et al., 2004).

Costs

Addressing acoustical considerations, as an integral part of theoverall design, can reduce design and operational costs and canprevent potentially difficult and expensive post constructionproblems and remediation. The added costs can be recaptured innearly one year of operation by constructing an “evidence-baseddesign” healing environment (where design decisions are driven byevidence from good research and real projects) that includes buildingacoustics and noise (Berry et al., 2004).

Reputation Resources Results

ISSUE NO. 32

To allow a private exchange of information in admitting andconsultation areas, good speech intelligibility, background

noise (for masking), and isolation are required.

Table 1: Common spaces and the importance of design aspects

NOISE AND ACOUSTIC CONCERNS IN HEALTHCARE

The primary noise and acoustical concerns in healthcareenvironments are related to patient comfort and rest, privacy,and environmental noise (outdoors).

Background noise levels should meet pre-defined criteriasimilar to those published by The American Society ofHeating, Refrigeration, and Air Conditioning Engineers(ASHRAE) for typical spaces in various types of buildings.Design criteria are best established in the early design stages.

Freedom from external distraction is important for alloccupants. Patients require freedom from externaldistractions so that they can get the rest that they require.Staff can also concentrate better when external distractionsare kept to a minimum.

Room acoustic design controls the persistence of sound in aroom (i.e., reverberation, echoes). Controlling reverberationwith appropriate finishes enhances speech intelligibility,creates a calmer environment, and limits the noise transferbetween spaces.

Acoustical privacy helps to maintain the dignity of patientswhile dealing with sensitive personal issues. In the US, HIPAAplaces importance on privacy, as does the American Instituteof Architects Academy of Architecture for Health (AIA/AAH).

Environmental noise concerns include impacts from:

a) road, rail, air traffic, and industrial noise on thehealthcare facility

b) noise generated by the facility on surrounding noise-sensitive areas, and on the facility itself

DESIGN CONSIDERATIONS IN HEALTHCARE

Room Acoustics

The many spaces in a healthcare facility will each havedifferent acoustical requirements. The amount and locationof acoustically absorptive finishes dictates the level of speechintelligibility within the space and helps create a comfortableenvironment. There are a variety of finishes available to meldwith aesthetic designs and functionality, including cleanroom acoustic tiles with a washable finish.

Sound Isolation

Space planning in the early stages of design can reduce soundisolation requirements but does not eliminate the need toreview partition sound isolation performance. Partitions(walls, floors, and ceilings) should maintain privacy and limitthe transmission of noises that cause distraction.

Background noise in the context of sound isolation refersto constant noises typically created by building services.Impacts are normally calculated based on manufacturers’noise specifications.

Freedom from distraction is evaluated based onanticipated internally generated noise from human activitysuch as speech, corridor traffic, or unusual mechanical noises(e.g., health monitor alarms, or intermittent or excessivelynoisy mechanical systems).

Privacy requires that speech cannot be understood. Speechneed not be inaudible to maintain privacy, only unintelligible(see Table 2). Factors that can short circuit the privacyperformance of walls include door positioning and HVACduct layouts. There are many ways to quantify and verifyprivacy levels including the Articulation Index (AI), PrivacyIndex (PI) and Speech Intelligibility Index (SII). HIPAAmandates privacy of patient information, but does notprovide specific directives for acoustical privacy.

The Sound Transmission Class (STC) or, preferably the FieldSTC (FSTC), quantifies the as-built sound isolationperformance of a partition.

Nursing stations should be distributed to reduce corridor traffic.Incorporating acoustical finishes around nursing stations and incorridors will contribute to good communication, create acomfortable work environment, and reduce noise transferbetween spaces. Patients will benefit from improved rest leadingto faster recovery.

Table 2: STC ratings and the privacy provided

The above performance factors must be assessed along withcosts and intended use to determine the appropriate STCvalue. Once the STC requirements are determined, a partitioncan be selected.

Partition design details are as important as the partitionselection. Back to back outlets, air gaps, partial height walls,service penetrations, and direct duct runs can all reduce thefunctionality of a good partition selection.

Mechanical Noise

Mechanical equipment noise can enter sensitive spaces inseveral different ways, each requiring different forms ofmitigation.

Air-borne noise is transmitted through both interior partitionsand the exterior facade. Sources include mechanical rooms(interior), rooftop equipment, and fans exhausting to theexterior via louvers or stacks. Mechanical equipment noise canalso come from neighboring buildings. Control of air-bornemechanical noise can be achieved using appropriate partitionconstruction and detailing, building facade design, siteplanning, silencers, acoustic louvers, barriers, and selection ofquieter equipment.

Duct-borne noise travels efficiently through ventilation ductsto any space that is serviced by the system. Duct-borne noise isbest reduced at the source by selecting quieter fans or byadding silencers. Duct layouts should incorporate space forsilencers. Typically, encapsulated media or no-media type arerecommended due to contamination concerns. Duct layoutsshould enhance privacy and sound isolation (see Figure 1).

Structure-borne noise is caused by vibration from mechanicalequipment entering the structure where it can propagateefficiently and be re-radiated as air-borne noise. Structure-borne noise is best controlled at the source using rubber or

spring isolators and inertia bases. Isolation of mechanicalequipment also helps to address impacts on vibration sensitivediagnostic/imaging and treatment equipment (e.g., MRI’s).

Diagnostic & Specialty Areas

Magnetic Resonance Imaging (MRI) equipment requires anenvironment with low vibration levels, but also is a significantsource of air-borne, structure-borne and duct-borne noise ifnot addressed appropriately. (See also Technote 33 on MRInoise and vibration.)

Audiometric testing, sleep disorder clinics, and other specialtyspaces require extra care in their design to limit backgroundnoise and external distractions.

Figure 1: Direct duct runs through rooms can compromise partitions, thus reducing privacy and freedom from distraction.

Indirect Benefits of Acoustics and Noise Design Recommendations

Many of these spin-off benefits offset or reduce the cost of noise control and, in their own right, are significant or primaryconsiderations for the healthcare provider.

Environmental Noise

There are several environmental noise concerns that oftenaffect healthcare facility design.

Noise from the facility can affect nearby receptors (e.g.,rooftop equipment affecting nearby residences). Modeling ofthe proposed facility, combined with measurements ofexisting noise levels, is recommended to determine impacts.Mitigation is best accomplished by proper use of acousticcontrols (i.e., mufflers, acoustic louvers, sound barriers) andby selecting quieter equipment.

The existing noise environment can affect the healthcarefacility (e.g., existing roadway and rail noise). Impacts arebest determined through site measurements and are bestmitigated by proper facade selection.

Noise from building services can impact sensitive spaces onsite. For example, rooftop equipment or fan noise fromlouvers may be heard through a window on a lower level.Mitigation is best achieved through a combination of facadedesign and site planning/acoustic control.

SUMMARY

The design of a healthcare facility requires consideration ofmany factors. As illustrated by this Technote, all of thebuilding systems overlap and impact one another andtherefore cannot be looked at independently.

A holistic, interactive team approach to acoustical design willproduce cost savings in the design process, in construction,and in future operations of the facility.

REFERENCESBerry, L. L., D. Parker, C. C. Russell Jr., D. K. Hamilton, D. D. O’Neill, and B. L. Sadler.2004. “The Business Case for Better Buildings.” Frontiers of Health ServicesManagement, 21(1), 3-24.

Blomkvist, V., C. A. Eriksen, T. Theorell, R. S. Ulrich, and G. Rasmanis. 2004.“Acoustics and Psychosocial Environment in Intensive Coronary Care.” Occupationaland Environmental Medicine.

Urlich, R., C. Zimring. 2004. The role of the physical environment in the hospital of the21st century: A Once-in-a-Lifetime Opportunity. The Center for Health Design.

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Environmental noise sources are plentiful around hospitalsincluding road traffic and mechanical noise sources. The impactscan affect the hospital and surrounding residences.