Significance of Acoustics in Healthcare Facilities
Noise in healthcare surroundings has severe impacts on patients, staffs, and visitors. Sleep disturbance and elevated blood pressure are two examples that have been observed in patients, while among staffs, emotional exhaustion and burnout are some of the impacts that are related with poor acoustical environments.
Evidence also shows that noise negatively impact patients physiologically. For example, in one study, patients stayed longer in the hospital after a cataract surgery during a period when noise levels were higher due to construction. Another example, it is also found that when noise levels are above 60 dBA, more medications were required by surgery patients post recover.
This also implicates that if noise in hospitals is properly addressed, patients will recover faster which will allow other patients to be treated.
Beside impacting patient’s physiological health, bad acoustical conditions can also impact perception of privacy, comfort, safety, and security for patients and their family. Generally, patients are more satisfied with the care provided by the staff if they are in a good acoustic condition.
Noise also has its consequences to the staffs. It can be a source of stress for hospital staff and may interfere with their ability to work effectively. Studies show that noise-induced stress was related to stress and annoyance among nurses. While other studies have shown that in most cases, noise did not significantly worsen performance by anesthetists and surgeons, the investigators found that when the noise levels are over 77 dBA, speech communication was possible only by raising one’s voice, and at the same time, speech discrimination reduced by 23 percent.
Primary aspects of Acoustics that need to be taken care of in Hospitals
The primary aspects that need to be paid attention to in healthcare facilities are as follows:
- Noise Level: The average noise level inside of hospitals reported in a study shows that in 2005, the noise level inside a hospital is around 72 dBA during daytime, and 60 dBA during nighttime. This is well above the recommendations given by World health Organization (WHO) guideline values which is 35 dBA during the day and 30 dBA at night, with nighttime peaks in wards not to exceed 40 dBA.
Note that there are two different issues related with noise level, first is the background noise level from HVAC system, medical equipment, and other noise sources, and second is the intermittent noise from speech, alarms, phone calls, etc.
Noise level inside of a room can be described by single number ratings such as NC (Noise Criteria) and RC (Room Criteria), or simply its equivalent noise level (LAeq) in dBA.
- Speech Intelligibility: Communication in hospitals is necessary both between hospital staffs as well as between patients and hospital staffs. Nurses and physicians are required to constantly comprehend and act on many types of auditory information in a high-paced stressful environment.
Speech Intelligibility are often described with several measures such as STI (Speech Transmission Index) and % ALC (Percentage Articulation Loss of Consonants).
- Speech Privacy: While it is important to maximize auditory information to be transmitted between people who need to communicate with each other, it is also important to minimize the audibility and intelligibility of their conversation to unintended listeners. This is to ensure that patients can discuss their health problems freely with their physicians without worrying that the conversation are listened by others.
Speech privacy achieved in a space is indicated by a privacy index (PI) which commonly divide levels of speech privacy to four categories which are:
- Confidential: conversations may be overheard but not understood outside the confines of the space
- Normal: conversation may be overheard and partially intelligible
- Marginal or poor: Most conversations will be overheard and intelligible to unintended listeners.
- No privacy: All conversations can be fully overheard and understood)
Example of Design Strategies to Improve Acoustic Environments
Some of the design strategies that have show improvements in the acoustic environment of hospitals are as follows:
- Usage of sound-absorptive materials in the room: One of the conditions that are observed to be contributing to the poor acoustic condition in hospitals is that most of the surfaces in hospitals are sound reflective. One of the most common solution to this is to use sound-absorbing ceiling tiles instead of sound-reflecting ceiling tiles. For example, a study in Sweden shows that by using absorbing ceiling tiles, patients of an intensive coronary care unit (CCU) show a better physical condition.
Sound absorption capability of materials is usually measured by NRC (Noise Reduction Coefficient)
- Space planning: To improve acoustic environment in hospitals, space planning can have a significant impact. This includes determination of room adjacency, taking careful consideration of room’s usage, level of privacy that is needed, and the desired background noise level, among other factors. One of the common considerations in space planning is to provide single-patient rooms instead of multibed rooms. Private rooms are less noisy, perceived to be more private, and permit more effective and confidential communication between staff and patients.
From the perspective of sound insulation design, rooms should be separated with partitions with sufficient sound insulation performance, with attention to sound leakages in partitions. The performance of the material is usually measured with ratings such as STC (Sound Transmission Class) or Rw (Weighted Sound Reduction Index).
- Eliminating or reducing noise sources: The common noise sources inside of a hospital are overhead paging systems, equipment, and staff conversations. The noise sources can be reduced by changing overhead paging with cell phones or wireless communication devices carried by staff, removing noise sources such as ice machines from the unit, turning off equipment when not in use, conducting group conversations in an enclosed space, and educating staff about the significance of noise, and therefore the recommendation to talk quietly.
- Usage of sound-masking systems: While still lacking enough scientific proofs of its effectiveness, sound masking systems have a potential to increase speech privacy for patients. Sound-masking can also reduce patient distractions to impact and intermittent noise. However, the usage of sound-masking systems should carefully consider other aspects such as speech intelligibility between patient and staffs or among staffs, as well as not to interfere with patient monitoring.
General regulations related with Noise in healthcare Facilities
The noise level inside a hospital is regulated through various means around the world.
This is an example for hospitals in Indonesia:
| No | Room | Noise Level Limit (dBA) |
| 1 | Patient’s room | 45 |
| – When asleep | ||
| – When awake | 40 | |
| 2 | Operating room | 45 |
| 3 | General room | 45 |
| 4 | Anesthetic room, recovery room | 50 |
| 5 | Endoscopy, laboratory | 65 |
| 6 | X ray room | 40 |
| 7 | Corridor | 45 |
| 8 | Stairway | 65 |
| 9 | Office and lobby | 65 |
| 10 | Equipment room and storage | 65 |
| 11 | Pharmacy | 65 |
| 12 | Kitchen | 70 |
| 13 | Washing room | 80 |
| 14 | Isolation room | 20 |
| 15 | Dentist room | 65 |
| 16 | ICU | 65 |
| 17 | Ambulance | 40 |
Those values however are often exceeded. Sound measurements should be regularly scheduled by regulating bodies or consultants to keep an eye on the compliance with these noise regulations.
If patients indeed spend less time in a hospital due to a better acoustic environment, the financial math quickly will show that investing in acoustic treatment with regular noise measurements will be far cheaper than ignoring the potential area of improvement.
A nice paperback originally written in 1923 from Jack. C. Haldeman: Noise in hospitals
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