Reduce Hospital Noise Complaints

soundproofing for hospitals

Hospitals are filled with noise; noise from patients and visitors, doctors and nurses, technologies and machines. The list goes on as to what creates noise in a hospital environment, but the ‘one-size-fits-all’ design does not take into account how these noises affect patients as well as staff. Furthermore, doctors are often prescribing plenty of rest in order to speed up the recovery process, but with loud noises around hospital 24/7 the patient often has to endure sleep deprivation and discomfort while healing.

Let’s begin by taking a look at a couple of acoustical studies conducted in hospital environments:

  1. The University of Chicago’s Pritzker School of Medicine evaluated the sleep patterns of 106 patients over the course of a year. The results of this study showed that the peak noise level that a patient was exposed to reached more than 80 decibels (imagine how loud a chainsaw is and pretend you’re trying to sleep just 20 feet away!). In addition to this, ICU noise levels reached 67 decibels and surgical wards, 42 decibels were reached. 42% of patients reported being woken up by noise and many reported sleeping less than average while in the hospital.
  2. The VA Boston Healthcare System used noise meters to measure the level of noise in a nine-bed unit which recorded up to 66 decibels in hallways and 74 decibels in the loudest patient room. How comfortable would you be trying to recover with a vacuum cleaner constantly running next to you?
  3. Johns Hopkins Hospital in Baltimore conducted a study which led to the results of 70 decibels in five cancer, pediatric, and medical surgical units.

These may just seem like a bunch of random numbers, but to put it into perspective, the World Health Organization recommends that the ambient noise level in a hospital should remain around 35dB and not reach more than 40dB; however, most hospitals average around 48 decibels – the equivalent of a large electrical transformer.

Not only does hospital noise affect the recovery time for patients, but it also negatively affects the staff that are exposed to the noisy environment on a daily basis. Most nurses report exhaustion, depression and irritability. Along with these side effects, there is often miscommunication between staff members as they are not able to hear their colleagues correctly when exposed to high levels of noise, putting both staff and patients at risk.

Finally, let’s touch on HIPPA compliance, better known as “you better keep my patient history secure or else…”. It is important for hospitals to take the Privacy Index (PI) into account when creating an active patient environment. PI is simply a percentage which relates to how audible a conversation is. A PI of 100%-95% represents confidential speech privacy, 94%-80% represents normal speech privacy, and anything below 80% represents minimal or no speech privacy. Acoustical solutions can easily be placed in hospitals, in between patient rooms, in order to increase the PI and allow a higher rate of patient-doctor confidentiality.

Long story short: noise affects patient recovery, it disgruntles hospital employees and a non-acoustically treated environment will lead confidential patient information to no longer remain confidential. With a few simple tweaks to the development of hospitals, such as acoustical membranes between patient rooms and sound masking in open areas, we can create an environment geared towards healing.

Commercial Acoustics Hosts Networking Happy Hour

commercial acoustics happy hour

Commercial Acoustics hosted a Happy Hour at Coppertail Brewery to commemorate the 1-year anniversary of our newest soundproofing division, and to highlight a number of successes over the past 12 months, including:

  • Closed Funding: We closed a growth equity round with Baldwin Beach Capital which has allowed us to expand into new markets in numerous major cities around the country
  • Launched New Division: Starting with Residential Acousticssoundproofing curtains, we’ve added a number of new product lines including Acoustical Absorption, Sound-Blocking Membranes, Sound Masking Cover, and Acoustical Consulting – a capability we shorten to ABC2
  • Distribution Agreement with Manufacturing Partners: We’ve reached an exclusive distribution agreement for our soundproofing membranes
  • Growth and New Hires: We’ve doubled in size over the past 2 years, bringing on new Sales and Product Development staff. We’ve just passed our first $1M in sales as a company, and hope to continue our growth in years ahead.

commercial acoustics networking happy hour

Soundproofing a Commercial Partition

Commercial Acoustics recently encountered a project where a commercial tenant was having issues with sound transmission from a tenant next door. The primary tenant was an automotive parts distributor, while the adjacent tenant taught karate classes. The “shrieks” from the kid’s classes came straight through the 2×4 stud walls, and were becoming a bigger issue by the day.

The walls were already fully constructed, and there was no budget for demolition and rebuild. Similar to other clients, the tenant was attempting to use absorption to dampen the sound coming through the walls, but was finding it ineffective.

Our in-house consultant went on site and determined the best solution was an OverWall Blokker, that could simply be adhered to the surface of the wall with Premium Vinyl Adhesive. There were a number of flanking paths as well, including the leading window into the space where sound was coming around the drywall and into the office.

After a brief consultation, the landlord was willing to split the cost of materials and installation. We delivered the materials in 3 days on site, and our installation team installed it over the course of the following day. Painting and finishing was outside the scope of our project, but sound testing indicated that the noise was reduced by 40-50% in this application. Typically, the OverWall Noise Blokker will be effective at reducing noise by 60-70% on low-mass metal stud walls, and 40-50% on wood stud. We do not recommend this product on high-mass (CMU or concrete) walls due to the need for decoupling.

Below are the before and after images of the soundproofing. The walls had an STC of 34 before treatment, and 40 afterward.

soundproofing commercial partition before
Side Office – Before Soundproofing Treatment
soundproofing commercial partition after
Side Office – After Soundproofing Treatment
soundproofing commercial partition before
Main Office – Before Soundproofing Treatment
soundproofing commercial partition after
Main Room – After Soundproofing Treatment

This treatment resulted in an approximate attenuation of 35-40% of the noise coming through the wall. While not ideal, it was achieved at 1/5th the cost of other solutions, and implemented in a 2-week timeframe. The solution achieved our client’s goal of attenuating the sound quickly and cost-effectively.

Using Absorption for Noise Reduction (NR)

acoustics dB-reduction

I approach this article with caution, due to the vast amount of misinformation and confusion between the concepts of absorption and sound-blocking.

At Commercial Acoustics, we begin each of our architectural courses with a strong distinction between these pillars of the acoustical world, and even with our architect clients, there is typically still 1-2 attendees that ask additional questions.

At a high level, sound-blocking principles should be used when you have noise transferring from a noisy area to a quieter one and would like to reduce this transmission, while absorption is used in large areas with echoes and reverberation control issues. However, there are a few select scenarios where absorption in the source room may be used to lower the overall dB level, and by result, reduce the amount of sound spilling into adjacent units nearby.

For example, a bar-restaurant in St Pete that we consulted with several years ago was experiencing complaints from tenants upstairs that were constantly annoyed by the din on the bottom floor. The restaurant already had fire-proofing completed on their corrugated metal ceiling, and refinishing the ceiling with soundproofing membranes and going through the approvals process was cost-prohibitive. However, we noticed that there was very little absorption in the space, and therefore noise from the patrons was reverberating in the space and creating an unnecessarily noisy environment. The principle of Noise Reduction (NR) tells us:

 

NR=10log(a2/a1)

a2: absorption in treated space

a1: absorption in initial space

 

This means that increasing the absorption in a space by a sizeable amount can result in reducing the overall decibel level. Specifically, increasing the absorption by 300% can lower the noise level by 5dB. Since there was so little absorption in the space, increasing by 300% was possible at a fraction of the price of re-constructing the floor-ceiling system above.

acoustics dB-reduction

Ultimately, this approach may be used for significant improvement in areas with little absorption as well as loud noise and reverberation that leaks into adjacent spaces. This includes bars and restaurants with nearby dwellings. However, this will only treat reverberant noise, and should not be used to treat direct field sources such as a speaker or television right next to a neighbor’s wall.

Resilient Channel – Best Uses and Worst Mistakes

soundproofing resilient channel

Resilient Channels, sometimes abbreviated as RC, are some of the most common components installed on projects requiring additional soundproofing (higher STC ratings). While they provide a significant improvement in decoupling the structure-borne noise in walls, they should not be seen as a panacea for all noise issues. Over the past 20 years, in both industrial and commercial settings, we’ve found resilient channels installed correctly in the field less often than not, resulting in poor acoustical performance. Below is a list of most common design and installation failures.

Common Mistakes with Resilient Channel

  1. Designing Resilient Channel for Metal Studs

The #1 benefit of RC is the ability to decouple structure-borne noise at a reasonable cost. This is an effective approach on wood stud or high-mass walls with a high stiffness index. However, a significant amount of commercial construction is completed with 20-gauge or 25-gauge steel studs, which already do an adequate job decoupling noise due to their intrinsic flexibility. The proper soundproofing method with these walls is to add mass via a soundproofing membrane or conventional construction materials, since additional decoupling will result in very little or no further improvement.

  1. Poor Installation Methods

The most common cause of failure of this system to meet performance specifications is lack of proper installation in the field. Resilient Channel is often installed by the same drywall hanging team that performs the rest of the drywall installation, in an effort to cut cost and reduce schedule. Without a professional that is very familiar with this, it is easy to run into the following issues.

  • Drywall Screws Going Into Both Resilient Channel Flanges: This needs to be inspected after every sheet of drywall. The RC is designed to have one screw lock it into the stud, and another screw attaches the 2nd flange to the drywall. However, the channel is not visible when screwing in, so it is very difficult to attach the fasteners to the exact spot. If any of the screws go through to the inside flange, the Resilient Channel is now fully locked in, and provides no soundproofing benefit.
  • Baseboards: When installing baseboards, many contractors place a wooden block to reinforce the bottom edge of the drywall. If this is done, the drywall is structurally locked to the studs, and the Resilient Channel is not effective.
  • Hanging RC Over Existing Drywall: When adding a 2nd layer of drywall, this should be done on the other side of the wall. If the resilient channel is installed directly over drywall (rather than studs), it creates a mass-air-mass condition that greatly reduces its effectiveness.

RC-Installation

  1. Attaching Cabinets or Bookshelves

Although strong in compression, resilient channel is very weak in tension, and therefore should not be used on walls where heavy units will be mounted, such as TVs, cabinets, or bookshelves. These units will either pull away from the wall over time, or if directly mounted to the studs, will greatly reduce the effectiveness of the RC.

  1. Using RC in Tight Space Confinement

Finally, RC requires an extra 2” per room used, due to the thickness of the channel and the extra sheet of drywall. In restricted spaces, this often becomes a limiting factor, especially in renovations or small units.

Deciding on Resilient Channel vs. Soundproofing Membrane

Ultimately, every architect needs to determine their STC requirements and the most cost-effective way to meet them. As an acoustical consultant, we typically recommend Resilient Channel for gypsum ceiling assemblies under open web truss and concrete decks. Furthermore, we’ve found it to be quite effective on walls requiring 2-hour fire ratings that do NOT require heavy loads suspended on them (anything over 50 pounds). In hotel rooms or apartment complexes, adjoining walls should strongly consider a range of soundproofing membranes that best meets their needs, often at a significant cost reduction from resilient channel while still hitting higher dB losses.

How Much Sound Absorption Do I Need?

Acoustic Panels commercial acoustics

At Commercial Acoustics, we approach every new absorption project with the same mindset – determine how much absorption is needed, then provide it in a cost-effective and timely manner. There are a few characteristics that typically demand some type of acoustic treatments – high vaulted ceilings, smooth walls, and no plush materials such as carpets and heavy drapes. When you notice an unwanted reverberation in your space, you can call an acoustical contractor, or just calculate your needed treatment.

Sabins Calculation Explained

To determine how much absorption you need in your space, follow the steps below:

First, calculate how many square feet the room is, and how tall the walls are. Multiply these units together, and you have the cubic volume of your space.

Then, add together the total square footage available in the room.

How absorptive is each surface? Check out our absorption coefficients here.

Total Surface Area = SA_floor + SA_walls + SA_Ceiling

The worst absorptive surfaces are hard, flat, and smooth. If they are parallel, that further worsens the situation.

The worst case scenario is a room of painted drywall that is a perfect cube, allowing resonant sound waves to reverberate continuously with minimal absorption or attenuation.

If there are no plush carpets or furniture in the room, you are likely to have additional echo issues.

Sound Absorption Example Calculation

Example 1: You have a 20’ x 20’ room, with 16’ tall walls. The ceiling and walls are painted drywall, and the floor is painted concrete. This is a gym used for yoga, but the instructor has a difficult time talking to students due to the echo.

The area of the room is 20×20 = 400 sq ft. This is not exceptionally large, and usually would not be a problem if it weren’t for all of the hard surfaces.

Total area of the walls is 4 x (Area of Each Wall), or 4 x 20 x 16 = 1280 sq ft

Finally, the area of the ceiling is the same as the area of the floor, which is 400 sq ft.

Now, let’s determine the total volume of the room. Because it is a rectangular prism, it is simply 20x20x16, or 6400 cubic feet.

Finally, we just need to determine how much acoustic absorption space we have. In this case, painted drywall has an NRC, or acoustic coefficient, of 0.1. That means it reflects 90% of the sound that impacts against it, and absorbs only 10%. Likewise, painted concrete only absorbs approximately 10%.

To find the absorption area of the floor, we multiply the area of the floor by the NRC of the floor. 400 sq ft x 0.1 NRC = 40 Sabins.

The ceiling and the walls follow the same approach:

Ceiling = 400 sq ft x 0.1 NRC = 40 Sabins

Walls = 1280 sq ft x 0.1 NRC = 128 Sabins

Therefore, the Total Sabins, or acoustic absorption in the room is 208 Sabins.

Now, let’s plug this in to the Sabins Formula: RT = .049*V/A

We find that the reverb time in the space is 1.5 seconds, which explains why it is so poor. Compare that against the table of acceptable reverberation times here.

*There are other considerations, although this simplified model does give fairly accurate results.

For instance, is there furniture, which can often increase the NRC of the room?

Also, parallel walls allow standing waves to develop, which amplify the reverberation in the room.

Check out our proprietary acoustical calculator tool, and determine how much absorption you need in your space today!

Common Absorption Coefficients for Acoustical Treatments

Multi-Surface Acoustical Coefficient
Smooth Concrete – Unpainted 0.2
Smooth Concrete – Painted 0.05
Wood 0.15
Rubber 0.05
Plywood 0.25
Walls – Acoustical Coefficient
CMU – Unpainted 0.35
CMU – Painted 0.05
Brick – Unpainted 0.05
Brick – Painted 0.025
Steel – Structural 0.1
Plaster 0.05
Gypsum 0.1
Glass 0.05
Flooring – Acoustical Coefficient
Linoleum 0.05
Terrazo 0
Marble 0
Carpet on Foam Rubber 0.55
Carpet on Padding 0.3
Low Carpet 0.2
Hardwood 0.3
Treatments – Acoustical Coefficients
Cellulose Fibers (1″) 0.75
Polyurethane Foam 0.3
Semi Rigid Fiberglass (1″) 0.75
Cork Tiles 0.7
Acoustic Ceiling Tiles 0.5

How to Quiet a Noisy Office – Drop Ceiling

soundproofing office Ceiling Noise Blokker

Office drop ceilings are extremely common in the workplace. From large call centers to modern design firms, the majority of workspaces have built-in acoustical ceilings, or drop ceilings, which oftentimes lead to acoustical noise issues. If you’ve ever worked in this type of environment, you understand how easy it is to become distracted by the conversations of others or to have your own conversation overheard.

Creating a quiet office is a key to better work performance and improving the well-being and stress level of employees. According to U.S. General Services Administration “Acoustical comfort is achieved when the workplace provides appropriate acoustical support for interaction, confidentiality, and concentrative work.” One of the primary flanking paths we see is when the office wall does not extend to the true slab above, and the sound simply travels up through ACT (Acoustical Ceiling Tiles) and over the drywall, and then back down on the other side.

To prevent this flanking, you need to either extend the wall up, or add a sound-blocking membrane on top of the ceiling tile, such as our patented DropCeiling Blokker. This product increases the absorption of the drop ceiling, while also adding a mass-loaded barrier that reflects sound back downward.

If you are budget-conscious, then simply adding 3/8″ drywall cutouts will block additional noise, but without the absorption characteristics, the reverberation in the space below may suffer.

Regardless of which option you choose, knowing the flanking path is the first step toward a solution.