Perhaps the most demanding acoustical space in the built environment is the healthcare facility. Acoustics are concerned not only with the quality of sound, but speech privacy, patient healing, and staff comfort. This acoustical challenge is met in a variety of ways, including sound-sensitive space layout and inclusion of private areas for the most confidential conversations. But the presence of numerous open spaces in healthcare facilities, especially areas invoking the legal protections of HIPAA, calls for something extra: electronic sound masking, adjusted to preserve privacy and avoid distractingly quiet “dead” spaces. In this article, consultant specialists offer guidance on appropriate selection and installation of these systems.
Engineer
Gregory C. Tocci
Cavanaugh Tocci Associates, Inc., Sudbury, Massachusetts
What exactly is sound masking? What does it do?
Sound masking provides a low-level, continuous electronic broadband sound. Sometimes called “white sound” or “pink sound,” it resembles the sound of an FM radio tuned between stations—a sort of low growl but barely perceptible. When properly balanced it sounds like air flow from a diffuser. Whether it is actually perceived or not depends on the sound environment and the level at which sound masking is set—usually at 48 dBA or lower. I remember setting up a tuned masking system in an office one evening and finding I was more easily able to hear it than I anticipated, only to come in the next morning and thinking it had shut down. However, it was still on. It was much less noticeable because the office was occupied and had the usual sounds of a busy, occupied office. But sound masking has been shown to be highly effective in protecting speech privacy and masking disturbing sounds or noises, especially by filling in those quieter interludes between noisy activities.
What is its role in maintaining HIPAA-compliant speech privacy?
Obviously, because of HIPAA, speech privacy has taken on growing importance. Hospitals have been cited by JCAHO and the Department of Justice for alleged HIPAA aural privacy violations and for inadequate privacy provisions for personal health information. It is a complex issue. In enclosed rooms such as physician offices and examining rooms which provide good sound isolation, adequate privacy can most often be expected. But in open plan spaces, including office cubicles, admissions desks, pharmacies, or even clinical laboratories—particularly in areas with hard-surface walls and flooring—several steps need to be considered to protect privacy: planning for adequate distance between speakers and unintended listeners, use of sound absorptive materials on surface areas, acoustical barriers that break the line of sight between speakers and unintended listeners, and electronic sound masking, which has been shown to be by far the most effective technique of all.
What about its role in noise abatement—e.g., counteracting corridor chatter and clatter—and, conversely, in counteracting deadly quiet that staff, in some areas, might find distracting?
If the background noise is low enough, sound masking can help, but obviously can’t be used to cover sound levels that are unacceptably high, without masking itself becoming unacceptably high. It is often asked whether electronic sound masking can be combined with paging systems. This is most often not the case, as masking systems generally require closer speaker spacing than is usually necessary for overhead page systems. Regarding areas that are “too silent,” electronic sound masking is the ideal solution by setting a minimum acceptable sound level and preventing ambient sound from falling below this level. Today’s masking systems can be programmed to accommodate different intensities of sound masking in different areas.
Would you discuss the two different types of masking system, indirect and direct?
Indirect systems, the more traditional and often cheaper approach, involve placing an array of speakers above the ceiling and aiming them at the deck at a particular angle. However, with overhead spaces as crammed as they are in modern facilities with cables, piping, ductwork and structure, indirect systems are often ruled out except, perhaps, for less congested areas of the hospital. A newer approach is direct sound masking, which uses a larger number of speaker devices set in the ceiling tiles themselves. This provides a more uniform level of background sounds in the spaces served, but requires the architect to coordinate ceiling speakers with other fixtures such as sprinkler heads, enunciators, lighting fixtures, and Wi-Fi antennas to avoid a cluttered look to the ceiling. The esthetic considerations here deserve a little more time in figuring out.
Final observations?
There are about 30 system choices available. Their design and performance can be evaluated using the ASTM E1130 Standard Test Method for Objective Measurement of Speech Privacy in Open Offices using Articulation Index. This standard provides hospitals the means for evaluating and documenting speech privacy conditions in open-plan areas. This documentation is useful in responding to JCAHO inspections questioning the adequacy of aural privacy in healthcare open-plan areas.
Acoustical Constultant
Dennis Paoletti, FASA, FAIA
Principal, Shen Milsom Wilke LLC, San Francisco
In which specific locations within a hospital are sound masking systems most commonly specified and for what purpose?
Any location that requires speech privacy is a candidate for sound masking, which helps to stabilize the background sound level in a space that is too quiet. Ironically, many spaces have become too quiet as a result of energy-efficient HVAC systems that slow down or turn off, and do not deliver air at sufficient velocity to generate background sound levels consistent with recommended noise criteria.
Potential spaces requiring sound masking may include: enclosed offices, open plan offices, and possibly patient rooms and conference rooms.
What are the pros and cons of different locations for sound masking systems?
Historically, sound masking loudspeakers have been located in a plenum space above a sound-absorbing ceiling. Other potential locations–for example, below a raised floor or exposed–are possible, but more challenging and can impact performance and cost in that the installation may require more loudspeakers, closer spacing, and special enclosures.
With regards to HIPAA compliance, how do you understand and interpret the requirement for “reasonable safeguards” to ensure speech privacy?
The original HIPAA authors were not aware that acoustical consultants could calculate and determine levels of speech privacy; hence, “reasonable safeguards” were introduced, which allowed for subjective, general conditions … whatever that may be. This included establishing “practical” methods, such as keeping specific/variable distances from those having conversations.
Because expensive real estate limits these distances, and most individuals do not understand the importance of background sound levels, achieving speech privacy cannot be ensured.
What type of noise do sound masking systems most commonly put out?
Sound masking systems actually utilize pink noise, which is “shaped” with frequency filters applied by the acoustic/audiovisual system designer. White noise is technically equal noise per octave and is a misnomer related to sound masking systems.
Music has long been identified as inappropriate for sound masking where speech privacy is a concern. It is not consistent in terms of frequency or sound level, and it is difficult to achieve agreement of music format by space occupants.
How has sound masking technology improved in recent years? What kinds of capabilities and features are today’s systems offering?
The industry has made great strides in technology to enhance the use and performance of sound masking systems in recent years. Most significant is the ability to adjust and control each and every loudspeaker in a system–often many hundreds of them, located above a suspended acoustic ceiling–remotely from a single laptop computer.
This has been a big timesaver. Computer programs allow for individual frequency adjustments per individual or zones of loudspeakers so that the resultant background sound generated in a space can be customized to the specific location, size, and function therein.
Some manufacturers are even offering packages of sound masking integrated with their ceiling panels. The difficulty with this approach is that if there is no acoustical consultant to guide the project, the client or end user may be getting more or less system than they need. An acoustical consultant can best determine, by technical calculation and their broad base of experience, where and when a sound masking system is appropriate—and what the expectations will be.
Where do sound masking systems fit into the overall acoustical design of a healthcare facility?
In the early days of sound masking systems, which were developed specifically for open plan offices with no full-height partitions, some thought it was a panacea for all noise problems. Now, 20 years later, the use of sound masking allows us to be more creative, and to carefully utilize sound masking systems where they are appropriate.
The key point for laymen to understand is that in order for a sound masking system to be effective, it needs to be located within the space requiring privacy, not the space generating the sound. Furthermore, some acoustically sensitive spaces, such as large conference or training/presentation/audioconferencing rooms, require low background sound levels and good interior room acoustics in order to function properly. Increasing the background sound level via adding a sound masking system is simply not appropriate.
Good acoustical design requires a combination of controlling sound and vibration from the HVAC/air distribution system, room finish material selection, and developing partitions to meet the privacy needs of the client/end user as determined by early establishment of acoustical criteria during programming sessions with the end users. Sound masking systems should only be a component of the total package.
Engineer
Ryan Bessey, PE
Acoustical Engineer, Stantec, Toronto
How should a sound masking system best be integrated into a space?
Sound masking should be located within the same space as the “listener” in order to mask noise coming from other areas such that it isn’t intelligible. It’s advisable to consistently use sound masking throughout a particular area so that it is not noticeable as users come and go from the space.
What are some options for where to locate the system?
Overhead installation tends to result in better distribution within a room and is more consistent with typical location HVAC noise, which sound masking systems tend to mimic. Plenum systems may be less noticeable than ceiling systems. Under-floor systems are rare, but are sometimes used for projects that are based on raised-floor designs.
Please share some best practices for sound masking system specifications.
Acoustics are complex and significantly affected by different factors in the room. Consequently, the expert advice of an acoustic consultant should be sought out when specifying a sound masking system.
Ideally, the sound distribution should be even, not too loud, and not too quiet. As such, a sound masking system will require calibration as part of the installation process.
With regards to HIPAA compliance, how do you understand and interpret the requirement for “reasonable safeguards” to ensure speech privacy?
This is a speech privacy requirement, which is dictated by the degree of sound isolation between spaces and the background sound level in the listener’s space. Reasonable safeguards would include providing an adequate degree of sound isolation between spaces through proper design of walls, floors, ceilings, doors, windows, and penetrations, and providing a reasonable level of background noise through careful design of HVAC systems or sound masking specification.
Again, the expert advice of an acoustic consultant should be sought to ensure adequate speech privacy will be maintained.
Are sound masking systems most commonly putting out white noise or music? At what point does sound masking reach a point of overkill?
Sound masking systems most commonly put out white noise with a balanced spectrum to provide optimized speech masking. In some cases, the use of music may be appropriate depending on the user’s tastes. Sound masking reaches the point of overkill once it is so loud that it becomes obvious and possibly annoying to the users. End users can benefit from the many studies on the optimum amount of sound masking to apply.
How has sound masking technology improved in recent years? What kinds of capabilities and features are today’s systems offering?
Sound masking has evolved from simple systems, consisting of speakers and noise generators, to programmable networked systems including individual frequency and level adjustments. These newer systems can even be programmed to change their noise output throughout the day to optimize sound masking treatment. There also have been advancements in installation options as sound masking can now be purchased built-in as part of the ceiling tile system.
When designing for acoustics in healthcare spaces, do you often try to design with the goal of avoiding the use of sound masking systems? What are some common design strategies for achieving this?
It’s very common to design healthcare spaces without the use of sound masking. There seems to be some resistance to the use of these systems, due to both the cost and a misunderstanding of the technology. The alternative is to provide a higher degree of sound isolation surrounding spaces, including the effect of all doors, windows, and penetrations.
The idea is to limit sound transfer generated by confidential activities into neighboring spaces. With sound masking, it would be possible to reduce sound isolation requirements slightly and still achieve an acceptable degree of speech privacy. HBI
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