Historic Fenway Hotel

soundproofing for hotel

Initially opened in the 1920s, the Fenway Hotel is due to be reopened later this year as a boutique hotel. While the transformation included cosmetic and functional upgrades, there was one portion of the hotel renovation that called for soundproofing expertise – the noise transfer between rooms.

Construction technology has come a long way in the past century, and with it have come benefits of additional privacy and comfort. Adding sound-blocking layers in a historic hotel, with limited space already, proved to be a real challenge. As we’ve discussed in previous articles, resilient channel can be a feasible solution on wood stud construction (which includes the Fenway), but in this case, the architecture firm couldn’t afford the extra several inches per room (not to mention the installation concerns).

The construction consisted of 2”x6” stud walls with immediately adjacent rooms, leaving limited options. Our team of acoustical consultants reviewed the geometries and target STCs, and provided our solution – Wall Blokker PRO on each side of the assembly, with Floor Blokker on the wood joist flooring systems. Within weeks, our team installed the solution and tested it for effectiveness. While the confined space limited the STC performance, we were able to surpass an STC of 50 at a cost-effective price.

The Fenway is a new type of clientele that is relying on Commercial Acoustics to provide a soundproofing solution on budget, within schedule, and to soundproofing levels that were previously unavailable with conventional construction techniques.

Soundproofing for Movie Theaters

When designing or building a new movie theater, it is critical to consider the movie-watching experience, from seating locations to auditorium reverberation and attenuation between adjacent theaters.

One of the top complaints we see in theaters is walls meeting high-STC requirements, but insufficiently designed to block the low-frequency noises that are most distracting (and annoying). As one consultant recently noted, STC should stand for Speech Transmission Class, since it is best used as a single-number guide in offices and other speech-constrained environments.

Ultimately, to reach acceptable dB transmission loss levels below 1000 Hz, you need at least a double-stud wall with a 2” air gap between the parallel studs. Traditionally, this has been used with multiple layers of drywall on each side – the most common combination we see is 2 layers one side and 3 layers on the other side. Unfortunately, this is a very inefficient way to achieve higher STCs, since the adjacent drywall layers are directly attached, meaning the sound travels directly through the layers. Furthermore, we’ve seen a significant rise in complaints with CMU-based walls, even when resiliently mounted drywall is incorporated and the cells are filled. These provide significant mass between the source and receiving rooms, but not enough decoupling between the rooms to attenuate low frequencies.

Instead, many architects and consultants are implementing soundproofing membrane layers in their designs. These offer some decoupling capability, while achieving higher STC and low-frequency attenuation than their corresponding gypsum-only walls.

For instance, consider a wall with gypsum-only (5 layers) versus membrane (2 layers membrane and 2 layers drywall). The former achieves a transmission loss of 48dB at 315Hz while the latter achieves 58dB loss at the same frequency. This 10dB increase is equivalent to cutting the sound power by 50%.

Some 3rd party theater-certifying bodies, such as THX, have specific low-frequency targets that are well above what a standard STC 70 wall will block. Therefore, it’s critical to consider not only the overall sound-blocking of a wall, but specifically it’s low-frequency attenuation capabilities.

Understanding IIC Claims for Soundproofing Underlayments

floor soundproofing

It’s a common occurrence: you see a 1-page data sheet claiming light-weight and inexpensive materials getting IIC ratings of 70 or higher. These data sheets are littered with incomplete information and undefined assemblies.

When you request the test data, it’s either difficult to attain, or when received, completely irrelevant.

So, where do you go from here?

Request Exact Attenuation Tests

The number one thing Acoustical Consultants recommend today is requesting exact attenuation tests from a third party lab. This removes the conflict of interest inherent between a technical and marketing team. When reviewing tests, find applicable configurations that are as close to your floor design, and make extrapolations from there if needed.

For instance, you may see an underlayment that shows an IIC of 55 on 6” light-weight concrete and acoustical ceiling (resiliently mounted 5/8” gypsum board), and with ¾” OSB and ¾” Gypcrete above. If your assembly design is similar, but with 1-1/2” Gypcrete, then you may add 1-2 points. The PCI (Prestressed Concrete Institute) has extensive data on incremental changes in building materials. On the other hand, if your reference design has no resiliently mounted ceiling, then you will need to remove 8-10 IIC points (as a rule of thumb). Better yet, request the same test from your supplier without an acoustic ceiling – top soundproofing vendors have numerous tests in dozens of configurations.

For further reference, see the list of 3rd party tests performed on the Floor Blokker membrane here. Acoustical technicians are available to answer any questions that you may have.

Exterior Noise Control

While there is significant literature and testing available for interior wall partitions, many planning and architect professionals run into issues of exterior noise control.

In Europe, where often-times it is required to perform a Sound Study prior to new development, the US and many other countries are in a build and react mode. This sometimes leads to liability concerns, when there are few mitigation options available after construction.

The most Common Complaints are roadway noise (linear source) and outdoor construction or industrial activity (point source).

1. Barriers

Outdoor barriers can be a very effective way to attenuate unwanted noise off of highways or from music venues. These are often seen as pre-cast concrete structures on the side of interstates, but may also include aluminum soundproofing panels near above-ground transit systems or flexible sound-blocking polymers near construction projects. The key to any effective barrier system is its height, proximity to the noise source, and barrier material. As a rule of thumb, the closer, taller, and thicker a barrier becomes, the more sound it will block. See the image below for an illustration.

exterior noise control

The initial path of propagation was D, the distance from the source to the receiver. The sound must now travel up and over the barrier, a total distance of (A+B). The greater tha (A+B-D) becomes, the greater the difference in sound attenuation. This total value is higher (given a fixed barrier height) if the barrier is located closest to the source or receiver locations. Ultimately, the barrier should have a mass of at least 2 lbs/sq ft to ensure the diffraction up and over the wall is the primary constraint, rather than the transmission loss through the barrier.

2. Spacing

Another rule of thumb is that the Sound Power decreases by 6dB for every doubling of distance from the source. This begins at 25′, then again at 50′, 100′ and so on. So a concert at 100dB would be 76dB at 200′ away – a significant drop, but still well above most noise ordinances. It may be less if the sound is traveling over a lake or other water body. However, the amount of sound loss may be improved by up to 10dB every 100′ with “Heavy Vegetation” (these should be large-leaf plants that are thick all the way to the ground).

3. Noise Source

Consider the noise source and how “annoying” it can be to the receiver. Steady drones from highways are less invasive than loud impulsive noises such as gunfire or hammering. As a rule of thumb, below is a table that illustrates noise coming off of a highway or primary road, and the suggested barrier height needed to achieve common background noise levels.

highway noise chart

4. Composite STC

Ultimately, the noise from the roadway or exterior source will be reduced by the facade of another building. However, when considering the level of attenuation a building provides, you must calculate the “Composite STC” – that is, a combination of the strong and weak facade elements that gives the total Sound Transmission Class of a building element. Unfortunately, a brick wall (STC ~55) with single-pane windows (STC ~25) will have a composite STC weighted heavily toward the windows, perhaps as low as 26-27 depending on the amount of window area. When this is the case, it is critical to treat the “low hanging fruit” (windows and other openings) to ensure that the overall sound-blocking most effective.

To learn more about soundproofing options, reach out to one of our consultants and schedule an initial meeting. We are headquartered in Tampa, FL, but provide soundproofing solutions across the Southeast and special projects across the US.

 

Commercial Acoustics – Florida’s Companies to Watch

commercial acoustics ceo walker peek

After another record-breaking year, Commercial Acoustics has been recognized as one of GrowFL’s Florida’s Companies to Watch in 2017.

Commercial Acoustics focuses on soundproofing and acoustical solutions, and has a strong market in Florida, Georgia, and Alabama. They have a number of innovative soundproofing membranes used in hotels, multi-family, and other properties to reduce airborne and structure-borne sound traveling between spaces.

Next year Commercial Acoustics aims to add 4 new positions, and experience another 50% growth as they bring their newest polymer membrane to the market in the Southeast.

Acoustical Consultation and Testing

Commercial Acoustics was contracted to perform consulting services for a multi-family property in upstate New York where residents were complaining of excessive noise, particularly from adjacent stairways and from footfall above. After initial review and discussion with the client, Commercial Acoustics traveled to the site and performed a number of acoustical tests for structure-borne (AIIC) and airborne (ASTC) attenuation between units.

After performing the tests, our analysis determined that certain products offered the most cost-effective solutions to increase the sound-blocking between the units at an affordable cost.

Brief Synopsis of Test Method

The airborne test was performed by placing a loud speaker playing pink noise in the corner of the room, and turned up so that it was at least 10 dB above the background noise in the receiving room. Measurements were taken in each room by frequency segments, from 100 Hz to 4000 Hz. Then, a calculation was performed to determine the Apparent Sound Transmission Class (ASTC) of the wall in question.

acoustical testing

A similar method was used to measure the structure-borne attenuation of the floor between and upstairs and downstairs unit. A tapping machine is used to drop 500g stainless steel balls onto the floor at a predictable height.

acoustical testing tapping machine

The tapping machine may also be operated remotely to save time while walking between the upstairs (source) and downstairs (receiving) units.


 

Investigation

After testing was complete, the room was swept to search for paths of sound leak between the units. The meter peaked near the stairwell wall, and again near the baseboards, where we predicted that acoustical sealant was not used. However, there was a significant peak along one portion of the wall, where an arrow was drawn.

acoustical testing

After taking the baseboards off and cutting the wall open, a knot was discovered in the wood that passed along the entire baseplate, allowing significant sound transmission from the source room to the receiving room.

acoustical testing

Furthermore, the ceiling in the lower unit was later cut open, and revealed a number of construction flaws. The tenants complained that when neighbors above walked on the vinyl flooring, the ceiling fixtures would shake. We discovered that the strongback that was designed to hold the web trusses together was not fastened to the trusses, allowing them to move independently. This resulted in significant weaknesses in the low frequency attenuation of the construction element.

acoustical testing

Worse yet, standard hat channel was used rather than resilient channel, resulting in a significant loss of decoupling in the floor-ceiling assembly.

acoustical testing floor

Recommendations

After the report and testing analysis was complete, we provided a list of potential solutions for the property, including likely lead time, cost, and predicted effectiveness. After careful review of the pros and cons of each solution with the client, a prioritized list was submitted as the final deliverable.

Since the ceiling channel could not be replaced easily, a flooring underlayment was specified under the LVT above to isolate footfall. Future phases of this property will undergo evaluation during construction to review for similar flaws. Acoustical sealant was used along the entire wall with the sound leaks, including liberal use of sealant along knots and other material defects.

The testing and solution were completed within 2 weeks of contract, and we continue to work with this General Contractor client on future vacation rentals and multi-family properties.

Noise Issues with Drop Ceiling

soundproofing ceiling flanking

One of the most common complaints we see in office and educational settings is flanking noise through open plenums between adjacent spaces. This is often problematic when walls between offices don’t go to deck allowing sound to pass directly through the Acoustic Ceiling Tile and allowing clearly audible conversations between neighbors. (Note: ACT are not designed to block sound but rather absorb echo in a large reverberant space). A common solution we see attempted is laying fiberglass batting on top of the ceiling tiles. However, this is strongly discouraged because batting is not STC rated and oftentimes maintenance staff struggles to keep it in place when accessing above the ACT.

A university in Florida came to Commercial Acoustics to address noise from their student government area spilling over into staff offices. Our recommendation? A new polymer based tile that installs above existing ACT to prevent the flanking path. Commercial Acoustics’ Drop Ceiling Noise Blokker is available in our Florida and North Carolina warehouses and shipped to the university campus during school break for installation. Installation is simple, taking just a few hours for just over 300 tiles.

soundproofing ceiling
Drop Ceiling Panels Above the ACT Grid

Restaurant Acoustical Absorption

acoustics in restaurants

While many restaurateurs struggle with acoustic issues, some are more critical than others. Take for instance, Tampa’s downtown Channelside restaurant Cena. A high-end Italian Cafe focused on upscale Mediterranean cuisine, the restaurant was a perfect storm of underlying acoustical concerns. The walls were painted gypsum with a significant square footage of windows. Meanwhile the tall ceilings created a large volume with little porous material to absorb the dinnertime conversation. The result – an echoey room that made conversing difficult.

With a limited budget and tight timeline before the holiday season, Cena management reached out to Commercial Acoustics for a cost-effective solution. We measured their reverberation time of approximately 1.1 seconds, relatively high for a commercial dining space. After simulating the proper amount and type of absorption material, we proposed the solution to achieve 0.7 seconds, ideal for this type of restaurant. The solution included 2” thick fiberglass clouds and panels – capable of absorbing the low-frequency discussions.

Within weeks we manufactured the ceiling clouds and panels in-house and coordinated installation. All fabric finishes were reviewed with the client and not only blended in but enhanced the existing décor. Installation occurred during closed business hours and was completed in a single afternoon. We measured reverb time afterwards and it met our target decay rates, but would it stand the true test? We met with Cena’s owner who was pleasantly surprised and stated “The panels really work! I had dinner with several friends and the place was packed and we had great ability to converse”.

We were able to provide this customized, acoustical solution before the busy holiday rush of patrons. Better yet, the manufacturing and installation took just over 3 weeks and we were able to deliver results to the client for under 6K.