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Learning Objectives

• Importance of noise reduction • The basics of sound • The role of acoustics • Acoustics’ impact on education environments • Workplace acoustics’ impacts on productivity • Effects of carpeting on acoustics • Noise reduction benefits of cushioned carpet backing • Sound absorption • Sound transmission


Importance of Noise Reduction • High-occupancy workplace, institutional and educational interiors can generate noise levels that may impact concentration, productivity and even healthcare costs.

• A study by the American Society of Interior Designers (ASID) reported that distractions are a significant factor in the productivity equation, further defining conversational distraction and uncontrolled noise as the primary categories.


Importance of Noise Reduction • According to the Technical Committee on Architectural Acoustics of the Acoustical Society of America, excessive noise and reverberation interfere with speech audibility, resulting in reduced understanding and in the case of classroom settings, reduced learning. For example, in many classrooms in the United States, the speech intelligibility rating is 75 percent or less. That means that, in speech intelligibility tests, listeners with normal hearing can understand only 75 percent of the words read from a list.


The Basics of Sound

• Sound begins from a point of disturbance, much the way ripples expand from a stone that’s thrown into a pond. • From that point, a series of pressure waves go out in all directions. • Vibrations travel through the air to the ears of the listeners and are processed by the brain and interpreted as sound. • “Noise” is unwanted sound, and “signal” is what a person is trying to hear. • In all sonic environments, there is background noise, and if the signal is not much louder than the noise, people will have difficulty hearing. • The objective of noise management is to control the pressure waves, typically through the use of materials that absorb the vibrations before they reach an area occupied by people.


The Role of Acoustics

• Acoustics play an important role in a variety of settings. • Education and workplaces are key environments where the addition of cushioned carpet can have a major impact on acoustics. • Other spaces include hospitality settings and public spaces. • In hotels, for example, guestrooms need peace and quiet from noisy corridors and neighboring rooms. • Public spaces like airports and libraries can be greatly impacted by the noises of foot traffic, cell phones, conversations, etc.


Acoustics in Education

• Acoustics are essential to learning environments. • Learning is intrinsically linked to communication and concentration. External noise is a major distracting factor in education. • The importance of acoustics is not limited to the classroom. Noise in corridors and public spaces can be an issue if those spaces are too reverberant, in which case voices become louder and louder to overcome the background echo. Sound is also an important navigational tool for the blind, who may have difficulty finding their way if sound is either reverberated or absorbed too much. • In a classroom setting, carpet with attached cushion is especially effective in reducing noise from feet and moving furniture.


Acoustics in the Workplace

• Sources of unwanted noise in the workplace are numerous and varied, and can affect large numbers of employees on a regular basis. • Examples of common workplace noises include foot traffic, phone or in-person conversations, machines and workstation noises. • Each of these sources of noise can combine with others to create distractions and a counter-productive work environment.


Noise Reduction in Open Office Plans


The Rise in Open Office Plans • Office walls have been steadily coming down in response to evolving needs in the workplace.

• Companies have invested heavily in new technology, all with expectations of greater productivity and positive impact on the bottom line.


The Cost of Time in the Workplace

• Intended benefits of open office plans have not been fully realized, and the cost is significant. • This is reinforced in work published by noted ergonomics consultant Dan MacLeod, CPE, which includes a rule of thumb equating one minute of time per day in the workplace to a value of roughly $100 over the course of a year. • When multiplied across a company’s workforce, it is clear that even small improvements in productivity can yield ergonomic and economic value. • One recent study, entitled Improved Productivity and Health from Better Environments, found that productivity improvements of only 0.33% could provide justification for significant upgrades in certain systems that impact the working environment.


Losses of Productivity in Open Office Plans

• In many cases, potential gains of open office plans may have been offset by productivity losses due, in part, to noise, according to the ASID study. • The results of the ASID study suggest that the problem is widespread. In fact, the study includes a survey in which 70 percent of the respondents (workers or employees) felt their productivity would increase if workspaces were less noisy.


Losses of Productivity in Open Office Plans

• Underscoring the problem, a follow-up survey conducted by ASID found that “business executives were largely unaware of noise problems in the workplace and, in fact, 81 percent were unconcerned about office noises.”


Cost Savings vs. Employee Satisfaction

• Some now see the open office as strictly an economic play, providing a vehicle for cost and space savings at the expense of occupancy quality. • Others maintain the original vision of positive cultural changes and employee satisfaction.


Cost Savings vs. Employee Satisfaction

• Whether the rationale is to promote better teamwork or simply to increase the number of people per square foot, open office layouts and the associated noise issues aren’t likely to go away any time soon.


Carpets Impact on Acoustics

• Achieving the optimum productivity improvement requires a comprehensive approach, specific to a facility and organization. Flooring specification is an important consideration for noise reduction. • Carpet helps meet acoustics standards. According to the Carpet and Rug Institute (CRI), it is 10 times more efficient in reducing noise compared to other flooring options.


Importance of Cushioned Carpet • One aspect of the ASID study evaluated the role and performance of carpeting in acoustic management. “Acoustic properties of a flooring system are strongly influenced by the addition of cushion in the commercial workplace.” It was further noted that commercial carpet with integral cushion provides “both superior acoustical and ergonomic properties.”


Importance of Cushioned Carpet • Case Runolfson, CFM, vice president of facilities management for the Irving Group in Washington, D.C., also commented on the situation, stating that “effective sound suppression is the most difficult challenge remaining in the open-seating-plan work environment.” With an eye toward solutions, he noted the benefits of a properly specified carpet cushion composite from the perspective of both acoustic management and the improved carpet appearance retention and life cycle.


Importance of Cushioned Carpet • Field installations support in-lab research on carpet cushion and acoustics. John Mazlin of the internationally accredited acoustical and vibrational engineering firm of CAMETS Acoustics states, “The absorption coefficient differences between carpets lies with the type of pile and its thickness. The manner in which the carpet attached to the underlay is very important, as is the closed or open celled nature of the underlay, open cell being much more acoustically desirable.”

• Therefore, commercial bonded polyurethane cushion with its open cell design significantly enhances the acoustical absorption characteristics over those of the carpet alone.


How Polyurethane Cushioned Carpet Backing Works

• Polyurethane technology for commercial carpet creates a unique molecular structure, forming a polymeric bond between the primary and secondary backing. The result is a unified composite material that improves the performance of carpet. • Based on acoustical studies and field experience, carpet with an integral polyurethane cushion can play an important role in a comprehensive noise management program.


How Polyurethane Cushioned Carpet Backing Works

• Carpet with polyurethane cushioned backing serves as an effective noise reducer by minimizing the sound of foot traffic, providing effective absorption of airborne sound and reducing sound transmission to rooms below.


Footfalls

• One source of uncontrolled noise comes from the surface noise generation of walking traffic, commonly referred to as footfalls. • In office spaces, this distraction level has worsened as workstations and walkways have become closer in proximity. • High density open office plans may have traffic lanes weaving in and around the placement of desks and computer stations, increasing the potential that those on foot disturb those at their desks.


Sound Absorption

• Sound absorption coefficients, the fraction of incident sound energy that is absorbed by a material, usually vary strongly with frequency. • A noise reduction coefficient (NRC) is used to grade the effectiveness of a material employed for sound control. Floorcovering Acoustics 0.3 0.25 0.2

0.2 NRC

0.1

0.015

0 Hard Surface

Carpet

Polyurethane Cushioned Carpet


Sound Absorption Studies on Carpet

• Studies reported by the Carpet and Rug Institute (CRI) and The Dow Chemical Company (“Dow”) clearly show the acoustic benefits of the carpet cushion composite as compared to hard surface floors or carpet alone. • R. King Herbert, FASA, an expert in architectural acoustics with Ostergaard Acoustical Associates, notes, “A material with an NRC of 0.25, for example, absorbs about one-fourth of the sound that hits its surface.”


Sound Absorption Studies on Carpet

• As shown in the Floorcovering Acoustics graph below, the carpet with the integral polyurethane cushion was found to provide a 25 percent improvement in NRC over the same style of carpet without cushion (0.25 vs. 0.20), a finding consistent with results in other studies.


Sound Transmission

• Transmission through walls, floors and other barriers is much greater for low-frequency sounds than for highfrequency sounds. • Sound transmission is measured between two reverberation rooms for at least 16 standard frequency bands.


Sound Transmission

• For convenience in comparison of different constructions, the sound transmission class (STC) rating condenses sound transmission information into a single number according to ASTM E-413. • STC is fairly accurate for human speech; however, for lowfrequency sound, such as a motor, fan or even music with strong bass, the perceived sound may be greater than that indicated by STC.


Sound Transmission Studies on Carpet

• The acoustics study by CRI also rated the so-called insulation-from-impact noise. • The higher the Impact Insulation Class (IIC) value, the greater the sound insulation properties.


Sound Transmission Studies on Carpet • Additional acoustical research, jointly sponsored by the Alliance for Flexible Polyurethane Foam (AFPF) and the Carpet Cushion Council (CCC) and conducted by Intertek Testing Services (ITS), measured the sound-absorbing capacity of commercial cushion under carpet.

• It demonstrates that the use of properly specified separate carpet cushion, expressly designed for commercial applications, can deliver as much as double the sound absorption of glueddown carpet alone. • The computer at ITS measured how long it takes for noise to dissipate in a room. To do this, it generates a brief, loud noise, first without any carpet, then with a glued-down carpet sample, and thirdly, with a sample of carpet cushion installed under the carpet. To determine the percentage of noise absorbed, ITS measures the different times the noise takes to dissipate.


Sound Transmission Studies on Carpet • Tests revealed that cushion plays a critical role in sound absorption. A commercial cut-pile carpet product direct-glued to a concrete substrate yielded an NRC of approximately 0.25 (1.0 represents 100-percent sound absorption). When a commercial bonded polyurethane carpet cushion was installed using a double-glue system with the same carpet, the NRC rose to 0.55. The sound absorption was more than twice that of the carpet alone. • Testing in two rooms, one upstairs and one downstairs, also measured the ability of carpet with cushion to lessen the sound transmitted between floors through the Impact Isolation Classification (IIC) test. A bare concrete slab, with an IIC rating of 19, improved to 58 with the addition of directglue carpet. When the same carpet was double-glue installed with bonded commercial polyurethane carpet cushion and tested, the IIC rating increased to 69.


Sound Transmission Studies on Carpet

• Independent industry laboratory tests confirmed the following Impact Sound Transmission ratings: – Bare Concrete: 34 – Carpet with Dow cushioned polyurethane backing technology (28 oz): 62 – Modular carpet with Dow cushioned polyurethane backing technology (24 oz): 59


Additional Benefits of Polyurethane Cushioned Carpet • Comfort Underfoot: Helps reduce heel-strike force and leg muscle response – two causes of standing and walking fatigue. • Durability: Contributes to carpet’s improved appearance retention by absorbing the pounding motion of foot traffic and supporting the weight of furniture without bottoming out. • Durability: Strong adhesion properties of polyurethane maximize tuft bind for the life of the carpet. Polyurethane carpet backing also helps minimize edge ravel, snags/pulls, and pilling/fuzzing. • Durability: Helps reduce likelihood of delamination and pile crushing and matting over time.


Additional Benefits of Polyurethane Cushioned Carpet • Moisture Barrier: Includes functional liquid barrier that impedes spills and dirt from penetrating the subfloor. Plus it allows for aggressive cleaning, including hot water extraction.

• Installation: Maintains flexibility over wide range of temperature and site conditions. Breathability of polyurethane carpet backing aids in the drying and curing of adhesives. Plus it facilitates seaming and pattern match during the installation process. • Improved Life Cycle: Creates a more durable, longer lasting carpet.


Conclusion

• Depending on the specific carpet construction, cushioned backing is an effective sound absorber at high frequencies and can make a space sound less bright. • The ASID study notes that the soft floor covering “contributes more than the measurable noise reduction values, creating an aesthetic ambiance conducive to lowered voices, heightened privacy and reduced distraction.”


Conclusion

• Properly designed and implemented, a comprehensive noise control program can have a positive impact on productivity by reducing time-consuming distractions. • Seek expert advice to understand acoustic characteristics for specific products that may vary from the results presented here.


Sources

Classroom Acoustics: A Resource for Creating Learning Environments with Desirable Listening Conditions. Seep B, et al. The Acoustical Society of America. 2000. American Society of Interior Designers (1999). Sound solutions: Increasing office productivity through integrated acoustic planning and noise reduction strategies [online]. Available: http://www.asid.org. MacLeod, D. How business can increase profits with good ergonomics [online]. Available: http://www.ergoexpo.com/new/increase_profits.html (February 22, 2001). Duffy, F. (1997). New Office. Conran Octopus Limited. Improved Productivity and Health from Better Environments: W. Fisk and A. Rosenfeld (Department of Energy, Senior Advisor to the Assistant Secretary for Energy Efficiency and Renewable Energy), Indoor Air, 7:3.


Test Questions

1. Noise is … a. All sound that reaches a listener’s ears b. Unwanted sound c. Only sound at higher decibels d. Only sound at lower decibels 2. Signal is … a. Sound a listener is trying to hear b. The optimum level of noise for a room c. Sound vibrations d. Background noise 3. High-occupancy workplace, institutional and educational interiors can generate noise levels that impact: a. Concentration b. Productivity c. Healthcare costs d. All of the above 4. In education settings, what noise is carpet with attached cushion especially effective in reducing? a. Gymnasium and theater sounds b. Corridor voices c. The sound of foot traffic and moving furniture d. Sound in a cafeteria

5. What’s the minimum amount of productivity improvements needed to justify significant upgrades in systems that impact working environments? a. Only .33% b. Only 1.4% c. At least 10% d. At least 25% 6. Over the course of a year, one minute of time per day in the workplace is valued at roughly: a. $50 b. $75 c. $100 d. $125 7. According to the CRI, compared to other flooring options, carpet is how many times more efficient in reducing noise? a. 4 times b. 6 times c. 8 times d. 10 times


Test Questions

8. Which is more acoustically favorable for a carpet’s underlayment? a. Delaminated design b. No underlayment at all c. Closed cell structure d. Open cell structure

12. ASTM E-413 condenses sound transmission information into a single number known as: a. The sound transmission class rating b. The actual sensory transmission metric c. The noise reduction coefficient d. The sound absorption reduction method

9. Carpet with polyurethane cushioned backing serves as an effective noise reducer by: a. Minimizing the sound of foot traffic b. Providing effective absorption of airborne sound c. Reducing sound transmission to rooms below d. All of the above

13. Which of the following flooring options achieved the best ASTM E-413 number? a. Bare concrete b. Wood flooring c. Carpet with Dow cushioned backing technology (28 oz) d. Modular carpet with Dow cushioned backing technology (24 oz)

10. Noise reduction coefficient (NRC) is used to: a. Measure insulation-from-impact noise b. Grade the effectiveness of a material employed for sound control c. Gauge sound transmitted through floors and walls d. All of the above

14. The higher the Impact Insulation Class (IIC) value: a. The greater the sound insulation properties b. The lower the sound insulation properties c. The greater the frequency d. The lower the frequency

11. What percentage improvement in NRC is carpet with the integral polyurethane cushion found to provide over the same style of carpet without cushion? a. 10 percent b. 15 percent c. 20 percent d. 25 percent

15. Carpet contributes more than the measurable noise reduction values. It also creates an aesthetic ambiance conducive to: a. Lowered voices b. Heightened privacy c. Reduced distraction d. All of the above


Notice: No freedom from any patent owned by Dow or others is to be inferred. Because use conditions and applicable laws may differ from one location to another and may change with time, Customer is responsible for determining whether products and the information in this document are appropriate for Customer's use and for ensuring that Customer's workplace and disposal practices are in compliance with applicable laws and other government enactments. The product shown in this literature may not be available for sale and/or available in all geographies where Dow is represented. The claims made may not have been approved for use in all countries. Dow assumes no obligation or liability for the information in this document. References to “Dow” or the “Company” mean The Dow Chemical Company and its consolidated subsidiaries unless otherwise expressly noted. NO WARRANTIES ARE GIVEN; ALL IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSLY EXCLUDED. This document is intended for use within North America Published July 2008. © 2008 The Dow Chemical Company 109-00804-1008TBF


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