Sheriff’s Office – Sound Masking

The Pinellas County’s Sheriff’s Office was struggling with a number of noise complaints. Among other things, they were concerned with the sound privacy in interview rooms, to ensure that interviews were conducted in a confidential manner.

So they contacted Commercial Acoustics. After an initial site visit, we prepared a solution that would provide significant speech privacy without the need for a major construction budget. By pairing sound masking speaker systems with additional soundproofing wall membranes, we were able to increase the STC of the walls while also masking background noise.

The combination of the two approaches yielded impressive results: primarily, that officers no longer needed to worry about being overheard while they worked (and were not distracted by other conversations). While the sound masking system was installed, tuned, and implemented in a single day, the soundproofing membrane for the walls required an additional several weeks to complete each of the 10 interview rooms. This is a level of soundproofing that many law enforcement agencies do not require, but which provides superior soundproofing for a wide array of applications.

For many clients, the benefit of sound-masking cannot be over-stressed. The highly-tuned speakers provide an exceptional ability to mask background noise, and thereby reduce the “dynamic range” that so many office employees find extremely distracting. The speakers are hidden from view, concealed behind the ACT. They do not interfere with voice recordings, and actually enhance the speech privacy over phone conversations. Affordably priced, at approximately $1.00-$2.50/square foot, it can make the difference between a noisy workspace and an acoustically-treated office.

Lake House Acoustical Treatment

At the Lake House room in a luxury, master-planned community in Lake Nona, Florida, an unexpected issue arose.

The aesthetics of the room were impeccable. The room was adorned floor to ceiling windows along the walls, and custom chandeliers in the center. The hardwood floor was especially unique – charred in an oven for hours, then sand blasted to remove the marks – it felt more like tile than traditional hardwood. All of the mechanical devices were run by a single, wall-mounted flat-screen device, including the projector, room divider, and air conditioning.

However, regardless of the premium finishes and expensive electronics, one problem remained identified. With all of these hard surfaces, the reverberation time in the space was surprisingly long. While local residents use the room for meetings or yoga classes, it became very difficult to communicate with the echo that they experienced. A phenomenon known as “speech intelligibility”, this is a common issue experienced in gyms, auditoriums, and restaurants.

Unwanted reverberation or echo occurs when areas have large volumes and smooth, hard surfaces that reflect the sound back inward. When this happens, humans hear reflected noises as new words are being spoken, and have a difficult time identifying exactly what is being said.

The solution is to add soft, acoustical materials into the space, allowing the sound to be absorbed into its porous mass. The sound is then transformed into thermal energy and dissipated into the environment. The amount of absorption needed in a space is determined by the specific geometry and materials contained within.

For the Lake House, our production team custom-fabricated 100 2’ Wide x 4’ Long x 2” Thick Acoustical Panels, fabric-covered in the desired texture and color. Within 2 weeks the panels were delivered to site, and installed into the corrugated metal deck of the large room. Testing before and after the installation confirmed a drastic reduction in reverberation, from 1.5 seconds to 0.58 seconds.

This reduction resulted in a significant improvement in the perceived acoustic environment in the space. When previously conversation was strained, it was now smooth and neighbors had little difficulty understanding instructions and dialog.

Overall, the project took 3 weeks to complete, and the turn-key solution was provided at under $11,000.

Wall Blokker vs Acoustically Enhanced Gypsum Board

Acoustically enhanced gypsum board, such as Quiet Rock or SoundBreak, is commonly used in the construction of high STC (sound transmission class) wall and ceiling assemblies. It contains a viscoelastic gel layer in the center which is sandwiched between two thin drywall layers. Uses include but are not limited to educational, healthcare, commercial and multifamily projects.

While they are ideal if space constraints are critical, there are other products that achieve a higher STC at a fraction of the cost if small footprint concessions can be made.

Soundbreak and QuietRock Alternatives

SoundBreak and Quiet Rock drywall does have its pros. They get hung like traditional drywall for a ‘fool-proof’ installation every time unlike resilient channel which has very challenging installation requirements. The material cost however is 5x more expensive than traditional drywall, and due to the core density, the weight of the product often causes increased labor costs from contractors. Whereas acoustical drywall is approximately 2 lbs per square foot, many EVA membranes are approximately 1 lb per square foot, and therefore much more easily maneuvered at height.

When analyzing cost and effectiveness, a strong VE (cost-saving value engineering) option for this product is a soundproofing membrane which would get hung on metal or wood studs underneath traditional drywall. Instead of paying a premium for a gel barrier within the drywall, installing both pieces separately will save substantial cost. The Wall Blokker soundproofing membrane combined with traditional 5/8” drywall will outperform acoustically-enhanced drywall by 3-5 STC points on the same assembly, roughly saving $1.70/sf vs. Sound Break XP. See data below:

Residence Inn Highway Soundproofing

A Residence Inn location was having problems with their guests complaining about highway noise in their rooms. The hotel had not done any acoustical testing nor treatment in the past, so it was not surprising that car noise would enter the rooms and disturb guests. This is often an overlooked problem by many hotels, including ones that are high-end. Since there are not many acoustical consultants offering either proper testing nor proper materials, most hotel managers are forced to tell their guests there is nothing that can be done to reduce noise in their room. However, there are simple solutions that are not only effective but also affordable for all types of hotels.

When we arrived at the location, we asked what rooms had the most noise complaints. We made our way to that area and started testing the acoustics. After we tested the sound coming into the room, we made our final analysis and came up with a solution for our client.

We realized the main problem for this hotel was the sound leaking through the windows. Our team recommended they hang soundproofing curtains over their windows to seal any noise “leaking” through cracks or small openings in the windows. Soundproofing curtains are made up of MLV (mass-loaded vinyl) which is designed to block unwanted noise by up to 75%.

After installing the soundproofing curtains, the noise coming in from the highway as well as noise complaints from guests were significantly reduced. By teaming with the client’s engineering and maintenance team, we were able to deliver a cost-effective solution within budget that has solved the majority of noise complaints that the hotel previously encountered.