Sarasota Aerospace Office

Testing and analysis were performed for a property manager working for a commercial property. One of their commercial tenants, an aerospace center at the property had concerns about sound attenuation between adjacent tenant units. Two adjacent legal firms, with very low background noise in their offices, could occasionally hear muffled conversations being held in the office next to them.

3 Airborne Tests were performed in accordance with ASTM E336.

  1. Between Suite 840 and 860, the eastern-most office
  2. Between Suite 800 and 840
  3. Between adjacent office space within Suite 840


Description of Tests:

3 Tests were performed at the property

Test #1: ASTC Test between Suite 840 and Suite 860

  • Measured ASTC of 43
  • Receiving room – general description: The room was furnished, with carpet and acoustic ceiling tile.
  • Source Room – general description: The room was furnished, and filled with numerous files and cabinets. It was an active legal office.
  • Relationship between rooms: The Source room was located directly adjacent to the receiving room and shared a wall.
  • All adjacent spaces were closed off with doors during testing.
  • Description of Test Assembly
    • 25 Gauge Metal Studs
    • 5/8” Type X Gypsum Board Each Side
    • R-13 Batting in Studs

Test #2: ASTC Test between Suite 840 and Suite 800

  • Measured ASTC of 39
  • Receiving room – general description: The room was furnished, with carpet and acoustic ceiling tile.
  • Source Room – general description: The room was lightly furnished. It was an empty office.
  • Relationship between rooms: The Source room was located directly adjacent to the receiving room and shared a wall.
  • All adjacent spaces were closed off with doors during testing.
  • Description of Test Assembly
    • 25 Gauge Metal Studs
    • 5/8” Type X Gypsum Board Each Side
    • R-13 Batting in Studs

Test #3: ASTC Test within Suite 840, between a conference room and an empty office on the westward side of the conference room.

  • Measured ASTC of 37
  • Receiving room – general description: The room was furnished, with carpet and acoustic ceiling tile. One line of walls was thin glass, while the opposite wall was windows looking out over the street below.
  • Source Room – general description: The room was lightly furnished. It was an empty office.
  • Relationship between rooms: The Source room was located directly adjacent to the receiving room and shared a wall.
  • All adjacent spaces were closed off with doors during testing.
  • Description of Test Assembly
    • 25 Gauge Metal Studs
    • 5/8” Type X Gypsum Board Each Side
    • R-13 Batting in Studs


The design and construction of the walls tested is sufficient to meet the needs of most office tenants.

There are few attenuation codes defined and available for commercial office applications, and no attenuation building requirements.

Per one leading publication (Architectural Acoustics, Marshall Long), the recommended Field STC (now titled ASTC) for Normal Privacy at Normal Voice Levels is 32. Furthermore, Confidential Privacy may be attained at Normal Voice Levels with an ASTC of 38. All 3 of the walls tested meet or exceed this criteria.

Table 1: STC ratings needed to achieve Privacy at Normal and Raised Voice Levels

If further improvements are required by the tenant, they should be focused on the mullions and baseboards, and if significant improvement is needed, then a topical solution on the walls will provide a 4-8 STC improvement above the current configuration. Sound Masking is also a feasible solution, but should only be considered once mullion flanking is reduced to minimal levels.

Findings & Recommendations:

After ASTC testing was complete, we also performed leak checks along the wall in each of the 3 locations. In all 3 circumstances, significant flanking occurred along the mullions on the dividing walls, as well as secondary flanking along the baseboards.

No flanking was apparent along the ceiling. Walls continued up to the deck above the Acoustic Ceiling tiles. We used ladders to inspect the duct and piping penetrations, and all were visibly sealed with batting and caulk. Workmanship in this area was better than we usually see for ducting and piping penetrations.

1. Mullions: In all 3 tested locations, the sealing around the mullion appeared to be airtight. In these cases, the mass of the mullion alone (1/8” extruded aluminum) was insufficient to attenuate the same amount of noise as the metal-stud wall. In this case, the sound traveled the path of least resistance through the mullion itself. In a nearby, untested area there appeared to be a small gap in the mullion gasket.

  • Recommendation 1: The overall goal is to add further mass to the mullion. This is a perimeter, pre-constructed member, so modifications being made should be fully-reversible and made as a last resort. That being said, if there is an option to drill holes into the mullion and add blow-in insulation or other filler that will act to improve the performance.
  • Recommendation 2: Another option would be to adhere a thin membrane (Mass Loaded Vinyl, Wall Blokker, etc.) to the mullion on each side. These membranes are 1/8” thick and may be coated to match the existing

2. Baseplates/Bottom Tracks: In each testing area, there was some secondary flanking through the baseboards.

  • Recommendation: Remove the baseboards and apply acoustical sealant along the bottom of the drywall to make this gap as air-tight as possible.

3. Walls: While the walls themselves are sufficient to meet most client’s needs and expectations, additional soundproofing may be required in special circumstances (especially where confidential or private information is being shared). In this case, there are a few options:

  • Recommendation 1: Add a layer of mass-loaded membrane directly on top of the surface. This may be done rather economically, but outlets and other penetrations along that wall will need to be extended. Thickness of the membrane is only 1/8” thick, and should be applied along the entire surface. Expected sound-blocking increase is 20-30%.
  • Recommendation 2: Add a 2nd layer of drywall on top of the existing surface. The STC increase will not be quite as much as a membrane layer, but may be quicker to install. Expected sound-blocking increase is 15-25%.
  • Recommendation 3: If both of these options are undesirable, then consider implementing a sound-masking solution in the adjacent offices to minimize the speech intelligibility and articulation index of those next door.

Orlando Condominiums

The Cayman Condominiums were undergoing a renovation, its first in 20 years. While the existing structure and design were acceptable from an aesthetic and functional perspective, the contractor felt that they needed to address the one major complaint they were receiving – noise.

Metal stud walls helped reach STCs in high 40’s and low 50’s, but the residents at this luxury location had higher expectations. During the renovation, they called Commercial Acoustics to review the existing design and as-builts, and bring some new ideas to the table.

While implementing a soundproofing membrane in the walls allowed a significant increase in attenuation between units, we also worked with the architect to re-specify doors that would not allow weak-link propagation paths from room to room (a major complaint that previous tenants had).

While the flooring contractor was already familiar with our attenuation underlayment, we still had a technical rep out on site to ensure flanking paths were addressed and installation quality met our standards.

By implementing additional soundproofing materials and auditing installation techniques, our team was able to achieve STC and IIC ratings in the unit at 58 and 60, respectively.

Tampa Office Acoustics

An open office area was struggling with reverberation in their space and called Commercial Acoustics to help. We visited and found that unlike most open offices, that have issues with sound masking and speech privacy, this office setting did truly have unwanted echo in the space. This was due to a thin carpet, corrugated metal deck, and painted drywall.

Our team fabricated acoustic panels, baffles, and clouds, and used them in the space to deaden the excessive reverberation. We self-performed the install over a few hours, and finally provided their employees and staff the acoustical peace they were looking for.



Tropical Smoothie Case Study

As with many restaurants, Tropical Smoothie was suffering unwanted reverberation due to hard surfaces in their kitchen and dining area. We came on site and performed a reverberation test, then implemented a unique solution that improved their acoustics and aesthetics; a custom-printed absorption panel. The printing is done on acoustically-transparent fabric that allows the sound to transition into the absorbing core, made of mineral fiber.

The panel was custom-made over a 2-week timeframe, and installed on site in hours.

Office Space Vibration Testing – Case Study


A property management firm has encountered complaints regarding structural vibrations in one of its commercial office properties in Lake Mary, FL. Specifically, occupants complain of annoying or distracting vibrations in the concrete slab, and some occupants have been concerned with potential structural integrity issues.

The property management firm has already hired a structural engineer to inspect the structure and found no safety issues. The engineer has suggested that the vibrating slab may be due to under-loading of the slab, since all of the occupants have not yet moved in, resulting in a lighter-than-designed live load. This results in serviceability issues due to footfall in certain areas.

Commercial Acoustics performed a vibration study to determine the root cause of the unwanted vibration, and whether the structure complies with ISO 10137 Standard vibration serviceability criteria.

NOTE: The criteria assesses only whether the structure complies with vibration related to serviceability and NOT for safety.


Testing was performed per ISO 10137 “Bases for design of structures – Serviceability of buildings and walkways against vibrations”.

Three uni-axial accelerometers were used to measure the vertical vibrations incurred during a standard work day on the 3rd floor of their building. The sensors were placed initially at workstation 4183, which was the location of one of the chief complainants. The complainant was also present at the time of the testing and noted that she takes motion sickness medicine throughout the day to prevent nausea.

It should be noted that certain individuals are more sensitive and susceptible to vibrations, even if these vibrations are beneath commonly-accepted levels, and our mitigations list some areas in the office that may be more acceptable for those employees.

Vibrations at a second location were also tested, but found to be lower in magnitude than workstation 4183. As identified in the structural layout (Figure 3), workstation 4183 was mid-span between the beams and joists crossing the floor, likely contributing to the greater vibration magnitude.

They were placed in a layout running horizontally across the floor, perpendicular to the W21x44 beams that were spaced 10’ apart.

According to the standard, the vibrations were described as Class 3, corresponding to distinctly Perceptible but not strongly perceptible.


Crystal Instruments Spider 20 Data Acquisition Unit, Serial #: 5462944

PCB Piezotronics Single-Axis Accelerometer, Part #: 393B04, Serial #: 36913

PCB Piezotronics Single-Axis Accelerometer, Part #: 393B04, Serial #: 36795

PCB Piezotronics Single-Axis Accelerometer, Part #: 393B04, Serial #: 36783

PCB Piezotronics Single-Axis Accelerometer, Part #: 393B04, Serial #: 30743

Source of Vibrations

Figure 1: Vibrations due to Walking

After review of the data, there is no pattern to indicate that the vibrations are due to mechanical equipment. This would usually be indicated by periodic changes that were of the same length and magnitude. A brief demonstration was performed by bouncing on the balls of the feet and simulating walking down the hallway. Both demonstrably influenced the transducers, indicating that the source of the vibrations is staff movement. As seen in Figure 1 above, each incident of significant floor vibrations corresponded directly to staff or technician movement. All of the five aforementioned events vary in magnitude and duration but represent the individuals nearest the testing equipment departing their desks for various tasks and returning to their desks.

After discussions with the staff, it was further verified that the vibrations were sporadic throughout the day. This is common in floors with intermediate spans (between 10 feet and 30 feet) because the structure has insufficient stiffness or mass to reduce some vibration.

Figure 2 outlines the five RMS (Root-Mean-Square) signals with the greatest magnitude. All are from the first two hours of the day, with measurements taken between 8:44 and 10:44 AM, presumably because that is when the majority of the foot traffic occurred on site.

Figure 2: Vibration Magnitude for Each Test, m/s2 versus Frequency

These vibration levels are well below the acceptable limits in ISO 10137, shown on the right side of Figure 2. This graph shows the magnitude of vibrations in acceleration (m/s2), which peaked at about one level of magnitude below the acceptable limits.

Figure 3: Structural Drawings of 3rd Floor

A second set of readings were performed at Testing Location 2, as requested once the team arrived on site. As seen in Figure 4, the magnitude of vibration at the second location was significantly less than the magnitude at Testing Location 1. This is likely due to the proximity to the larger beam in the core of the building. Testing Location 1 is located at mid-span between the larger, stiffer beams.

Figure 4: Magnitude of Vibrations at 2 Different Testing Locations

Path of Vibrations

The testing data indicate the vibrations are propagating through the deck from adjacent footfall. The flooring system consisted of thin Carpet on Concrete (3” Concrete on 3-1/4” Corrugated Deck). No cushion or underlayment was installed under the carpet.

Mitigation Options

Since the office space is fully built-out and in use, construction methods such as stiffening the floor with additional beams are not desirable. However, a number of options are still available, listed below.

  1. Vibration-Reducing Mats:
    • Type: Topical or Underlayment: Since the flooring system is already installed, it would likely be cheaper and faster to install a topical sound reducing mat on top of the existing floor system. A pad such as Pliteq’s GenieMat FIT would be acceptable. This mat will isolate the footfall before it becomes structure-borne in the slab, and will result in a reduced vibration load in the nearby workstations. Other products, such as Commercial Acoustics’ Floor Blokker would be acceptable if installed under the carpeting.
    • Location: Hallways or across the entire floor: It is recommended to only install this pad in major walkways, since that is where the majority of the footfall is occurring. While this will not isolate footfall in certain pods, it will address the majority of the footfall while saving significant cost in material and precluding the need to move the existing office equipment.
  2. Rearranging Office Employees
    • As mentioned above, some office employees are more susceptible to vibrations and movement than others. Relocating these staff to more stable portions of the building, especially near the corners and directly next to the central beams will minimize the level of vibrations they feel. Corner locations nearest to two thick beams will be the most stable.
  3. Future Designs
    • By placing beams and joists closer together, the structural engineer may greatly increase the stiffness of the structure so that vibrations due to footfall are not perceptible by employees. Likewise, keeping the same span lengths the same but increasing the depth (and therefore mass) of the floor will result in a heavier floor that will respond less to human-induced movements.
    • Simply implementing a dampening underlayment during construction will also reduce the acceleration induced from human movement on the concrete slab.


The vibrations in the office space, while clearly perceptible, were not above the suggested thresholds identified in ISO 10137. While this is a good indicator of the serviceability of the structure, implementing Mitigation Options listed above will reduce the vibrations felt by employees and staff in the office area.

Student Housing – Case Study

CA Ventures is known for developing well-built, high-performing student housing complexes nationwide. When they were looking to develop a multifamily project close to Auburn University, comfort, aesthetics and amenities were a top priority. Located in the heart of downtown Auburn, Evolve Student Apartments stands 9 stories high, fully furnished with the highest level of amenities for residents.

The desire for a high level of tenant comfort and privacy began early in the design phase when the architectural firm contacted Commercial Acoustics to discuss wall and flooring assembly treatments. Unlike other student housing and mixed-use projects we’ve worked on such as The Village Promenade and 9 on Canal at Ball State University, Evolve’s sound concerns were from adjacent apartment dwellers, not external noise entering through windows from bars, street noise or shopping plazas. Consulting on the project we provided technical data, modeling out various assemblies and costs to ensure a target STC of 50+ would be achieved.

Instead of hanging multiple layers of drywall where you get diminishing returns and a longer installation time, our 1/8” Wall Blokker sound membrane was installed directly on the wood studs easily and fast with no seam taping required. By having the ability to consult and discuss with the architectural team we were able to increase the STC of the demising walls, reduce cost and achieve a quality living environment for tenants.

Tampa Upscale Hotel – Case Study

An upscale hotel reached out to us because they had been experiencing noise complaint issues since opening 3 years ago. During this time period, the hotel has used GSS (Guest Satisfaction Survey) Scores and comments to determine the areas in which noise complaints are derived. The hotel team’s initial observation is that the windows are transmitting noise and that the hotel doors are loud and disturbing the clients. The speakers at the hotel bar are also creating complaints for guests staying within that vicinity.

As these sound transmission issues are post-design and -construction there are limited design modifications and testing is required for successful recommendations to be made. Freeway & Roadway traffic, impact doors closing, loudspeakers, etc. can all generate airborne and structure-borne noise levels louder than other typical sources (speech, television, walking, etc.).

During our walkthrough performed on April 26, 2017 we confirmed with our Class 1 SPL (Sound Pressure Level) Meter that the majority of the sound in several rooms was being transmitted through the windows and sliding glass doors of the rooms. In addition to sound transmission the hotel doors were quite loud and vibrating the interior corridor walls when shut. The speakers in the hotel bar were directly mounted to the concrete allowing direct propagation of structural vibrations into the rooms nearby – this was confirmed with the corresponding noise complaints often filed in this area.

Test Method:

The following rooms were tested during the evening of May 26, 2017. A class 1 SPL meter was placed in room 359 to determine the peak noises occurring throughout the evening from the hotel bar. Hourly tests were conducted in rooms 310 and 231 to measure traffic noises. Qualitative data was measured in room 231 and room 310 as well, including how many audible noises were detected over a 1-hour span.

Test Results:

During that time, the most common audible noise from outside the room was Street Traffic, where a car could be heard passing almost every minute on average. While the cars could be heard above any background noise (Air Conditioning provided a background level of approximately 40 dBA), the sounds often did not exceed 55 dBA on the east side. Street Traffic was more disruptive on the express way side.

Note, the testing for each room was for 60 minutes, and done concurrently. There were other miscellaneous peaks in noise that occurred, including occasional toilet flushing or talking from exterior sidewalks, but these occurred infrequently and at low dB values.

As indicated in the tables above, windows facing the expressway were consistently louder than those facing east side. These were monitored throughout the night, and were measured at 47.1 dBA on the expressway, versus 40.6 dBA on the east, on average. The readings from the expressway were also characterized by higher dynamic ranges (larger differences between quiet and loud) that typically correspond with more complaints.

It should be noted that while the vertical shades in each room are effective at blocking light, they made little or no difference in the sound level coming through the windows.

Doors being slammed were a consistent, disruptive event throughout the night in all 3 rooms. It was noted during the walk-through that the doors are quite heavy, and while that improves the attenuation from the door itself, they make a loud thud when closed due to the lock of door closers.

Summary: Primary Issues and Mitigations

In order to save unnecessary cost, it is recommended to perform a brief follow-up study with a pilot room window to determine exactly how many of the hotel windows should be reinforced. This may not be necessary for many of the windows that do not directly face the east side or the expressway. There are several options to improve the STCs of the windows, with various costs and STC improvements associated with each.

Figure 1: dBA Values in Room 359 by Hour

Apparent Sound Transmission Class (ASTC) Testing:

Description of Test:

1. Airborne Test (ASTC) was performed in accordance with ASTM E336 between units 210 and 212 through the shared wall

a. This test was used to determine how much sound the wall assembly blocks between adjacent units.

b. The wall assembly tested was presumed to be, but not confirmed:

i. 1 Layer of 5/8” Type X Drywall One Side, 2 Layers of 5/8” Type X Drywall One Side, 25-Gauge Steel Studs 16” o.c. and R-13 fiberglass insulation batting in the cavity

ii. The wall assembly also included a solid-core door in the center, a 4” air gap, and another solid-core door. The doors did not have door sweeps or solid thresholds, but instead lightly grazed the carpeting as they closed.

Summary Findings & Recommendations:

The tests indicated an ASTC value of 47 for the walls separating rooms 210 and 212. While this number is above the Florida Building Code for multi-family units (requires a field value of 45), it just below what is typically implemented in hotel designs (design values of 55 to 60).

After testing was complete, a brief leak check was performed to determine where the majority of the sound was located. In the case of the first room, the sound level at the wall was 42 dBA, but reached 46 dBA at the door, and 48 dBA at the base of the door. This indicates that a more substantial door sweep or threshold may be sufficient to reduce noise coming through the entire wall assembly.

Likewise, the doors into the hallway measured 62 dBA at the door, and 69 dBA at the base. A more substantial door sweep or threshold at this location may also further reduce the noise being transmitted from the corridor to the rooms.

Statement of Conformance:

Airborne sound attenuation tests were conducted in accordance with the provisions of ASTM E336-16, Standard Test Method for Measurement of Airborne Sound Attenuation between Rooms in Buildings. Sensitivity checks were performed before and after testing to ensure the equipment was properly calibrated.

The testing described, the results calculated, and this report fully comply with the requirements of ASTM E336-16. No exceptions were made during this test.

The results stated in this report represent only the specific construction and acoustical conditions present at the time of the test. Measurements performed in accordance with this test method on nominally identical constructions and acoustical conditions may produce different results.

The test environment consisted of a furnished hotel room that included a living area. The source side of the experiment was in room 210. The two rooms were mirrored around a separation wall, with length 26 feet, width of 13 feet, and height 9 feet.

All doors were closed to the adjacent spaces.

A Nor131 Sound Pressure Level meter was used for all tests, Serial # 1313740, last calibrated on October 10, 2016. A Nor1251 Sound Calibrator was used for sensitivity checks, Serial # 34824. The meter and calibrator were hand-held.

A Pyle 18” Loudspeaker was used as the sound source for the ASTC tests, with white noise as the sound type.

Appendix A: ASTC Test Data

Table 7: Transmission Loss by Frequency

Figure 2: STC Curve for Rooms 210-212

Residential Bathroom Case Study – Tampa, FL

One of the problems that many homeowners face which not too many people think about is all the noise that can come from a bathroom, such as a toilet flushing or water running through the drain.

This was a big problem one of our residential clients in Tampa, FL had. During their family dinner, they could hear the water running from the toilet as well as some of the drainage coming from the kitchen. This was clearly very disrupting when they were trying to spend quality time together. The noise would also distract them while having guests which became embarrassing and quite bothersome.

After our team came in and did an acoustical analysis, we decided that the best solution for our clients was to surround the plumbing with a thick lagging which is made up of 2 parts, mass loaded vinyl (MLV) and batting. The MLV provides a layer of soundproofing which deflects the sound coming from the plumbing. The batting adds an extra layer of soundproofing as well as absorption for any resonation caused by the kitchen and bathroom plumbing.

The whole installation took approximately 3 hours. We applied lagging to over 50’ of pipe. This entire process dramatically decreased the sound of water above and the family was finally able to enjoy their home, free of distractions.

Gym Sound Treatment – Case Study

A gym reached out to us in search for a solution to the noise issues they’re having. They are located on the 2nd level of a commercial structure surrounded by a day spa, retail store and office space. The structure is dealing with reported sound transmission through the walls and flooring assembly between tenant spaces causing concern and complaints.

As these sound transmission issues are post-design and -construction there are limited design modifications available and testing is required for successful recommendations to be made. Weight drops, impact noise of weight machines, loudspeakers, and other noise sources can all generate airborne and structure-borne noise levels louder than other typical sources (speech, television, walking, etc.) associated with office buildings.


Our client has been in operation since December 2016, and since that time has encountered numerous noise complaints. These have originated primarily from three adjacent tenants: a spa (directly adjacent), health care facility (below), and to a lesser extent, a retail store (below).

Prior to build-out of the space, our client hired a different acoustical consulting firm to give design guidance and perform structure-borne testing relevant to weight dropping above. This design was reviewed as part of this scope, and found to be sufficient.

The tenant implemented these designs during construction, including the installation of a floated double-gypsum ceiling and sound-insulating underlayment where the sensitive health care facility neighbor was located. Airborne field testing was performed prior to project completion and was found to be effective. That testing was not reviewed as part of this assessment.

Further noise mitigation efforts have been implemented, including the following:

1. Moving free weights from the center of the gym room to the exterior, and moving dead-lift machines closer to the exterior

2. Closing the class training area door permanently (garage-style vertical lifting door) that would otherwise be open

3. Minimizing use of the Combat Training Class (CTC) area, which involved additional weight-dropping (especially medicine balls)

4. Treating the dead-lift area with large, absorption pads to cushion weights dropped

5. Adding signs to minimize weight-dropping in the gym

After performing airborne and structure-borne tests on site (see Appendix A), performing a site inspection, reviewing previous acoustic assessments, and conducting interviews with nearby tenants, the following mitigations are presented as additional options to consider:

Table 1: List of Options to Consider for Further Noise Mitigation

Review of Individual Tenants:

The initial assessment performed by the previous acoustical consultant focused on the health care office space below, and did not address the adjacent tenants. At that time, the company type for the adjacent tenants were unknown. Typically, “Salon and Spa” type businesses require a stricter than usual noise requirement, which was not reviewed.

1. Spa

While testing was performed in this space, a severe vibration was noted approximately halfway through that required the test to be restarted. This was due to the industrial washing machine in an adjacent room that shook the slab violently. The startup and cooldown frequencies of the machine caused the walls and cabinets to shake audibly. This may indicate that the slab lacks sufficient modal mass for this application, and may be treated by using adequate vibration-reducing steel springs/neoprene pads cantilevered under the washing machine.

It was noted after discussion with the construction manager that the pour was done in a continuous manner. We visually confirmed this assessment, as the only “pour break” visible in the slab was at approximately Spa Room 3, where the vibrations were no longer noticeable. By using a single-pour continuous slab in this space, the opportunities to minimize vibration through the slab are extremely limited. While a thicker underlayment may reduce some of the vibration, another option would be to add a control joint in the flooring system. As noted below, it appears that the primary beams run parallel to the proposed control joint location, so that it would achieve maximum effectiveness. A saw cut should run as deeply into the slab as structurally allowed, and should be filled in with acoustical sealant.

We noted that the ropes are almost inaudible in the gym, but once the energy is transmitted into the slab, it transmits easily into the adjacent spa and from there into the walls and air. This may be easily addressed by adding a topical sound-absorbing pad to the area where the ropes are striking the slab. While placing a thick underlayment under the ropes is a simple solution, it will not be necessary if the slab is isolated.

If a thicker padding is preferred, consider Pliteq’s Genie Mat FIT. This is a heavy duty, durable mat that will reduce transmission into the slab.

Figure 1: Floor Slopes Down Where 15mm Underlayment Is Not Applied

Further improvements may be achieved by isolating the spa walls from the concrete slab. The structure-borne propagation in the slab is transmitted directly into the walls since they are connected directly to the slab. A proper isolator or decoupling membrane placed underneath the track will greatly reduce the airborne propagation into the individual spa rooms.

The ASTC test (Appendix A) performed in this space indicated that the gym speakers are not a significant concern for the tenant. Furthermore, it was noted that the gym environment held its speakers at a lower level than similar gyms of similar size. The airborne noise was further masked by the individual, independently-controlled speaker systems in each spa room.

Figure 2: Area Near the Spa Chained Off – Even Jump Roping Caused Significant Shaking

Figure 3: Hallway Next to Spa Where Testing Was Conducted (See Appendix A) – Sufficient ASTC of 53

2. Health Care Facility

It was extremely quiet in this space, so that very little noise was masked from above. This made the structure-borne noises from above more audible than they would typically be in an office space. By using a sound-masking system, the “thuds” from above may be completely inaudible.

While the initial consultant memos suggested using thick underlayment in this area and moving the free weights, it did not specifically call out keeping equipment and machinery decoupled from the floor. It was noted that the machine presses are bolted through the underlayment directly into the concrete below, significantly impairing the underlayment’s ability to break the vibration path (much of the vibration can travel directly from the machine, through the bolts, into the concrete slab). Either unbolting the machines, or using an isolator in this area, may allow the vibrations to be absorbed prior to entering the concrete slab below.

Figure 6: Machine Presses Bolted Directly Through Underlayment Into Concrete

Figure 7: Deadlift Treatment Has Been Largely Effective

A brief demonstration of the previously-treated dead lift areas versus the machine presses indicated the majority of the vibration in the slab below is now coming from the machine presses.

Figure 8: Isolated Ceiling Below

Figure 9: Depth of Isolated Ceiling Seen From Below

3. Retail Store

The tenant has noted that it can occasionally hear or feel the vibrations in the rear of the retail area and in the break room. The complaints are minimal due to the masking music in the retail space, although heavy weights were occasionally audible. The vibrations heard in the retail store are likely from two sources. First, the areas directly above the retail store do not have the thick 15mm underlayments, which may result in some impacts coming through. However, we believe it is more likely that the sound is coming from the machine presses that are bolted to the floor to the west.


The use of a continuous 4” concrete slab for a second-floor gym introduces a number of vibration paths into local, adjacent spaces. While certain mitigations have been and may be considered, the best scenario is to isolate the slab from adjacent tenants or provide a thicker isolation pad in order to achieve acceptable performance.

Upon completion of this initial assessment and once noise mitigations have been implemented, a follow-on assessment performed over night when few or no tenants are in place (and mechanical and HVAC equipment may be turned off) may allow precise assessment of exactly which equipment is causing the most issues.

Since there are no applicable building codes for a gymnasium-to-tenant wall or floor-ceiling system, and since numerous noise mitigation efforts have already been undertaken, it is our assessment that the gym has made reasonable efforts to reduce the noise in this space to an acceptable level.

By reviewing and implementing one or more of the Options to Consider listed above, further noise reduction may be achieved and audible levels in adjacent tenant spaces reduced.

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.