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February 27, 2014  by Great Expectations, Exceptional Results
A Tale of Three Noisy Box Plants

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The Client

  • A box converting plant in central Washington.

The Issue

  • A citation from the Washington Division of Occupational Safety and Health (DOSH) for conditions which exposed employees above the permissible exposure limit of 90 dB (time-weighted average).

The Law

                                       Permissible Exposure Limit = 90 dB 

  • According to Washington and federal OSHA regulations, employers with employees who are exposed to 90 dB or above (as a time-weighted average) are required to investigate and implement engineering controls. In essence this means that ear plugs are no longer good enough. They needed to find a way to reduce the workplace noise levels.


  • PCA Health and Safety Consultants and its sister company, Dyad Noise were brought in to assess and reduce noise levels.
  • PCA conducted noise dosimetry – measuring a person’s noise exposure over the course of a work shift – for 86 employees and found that more than half were exposed above 90 dB.
  • Dyad Noise collected frequency band measurements from high noise areas, observed employee work practices, interviewed staff and determined how resources could be used to make the largest per-dollar impact without disturbing regular work and maintenance practices.

The Solution

  • Dyad developed plans and strategies, ultimately using a variety of materials to absorb and/or contain noise as well as to reduce noise at its sources.
  • Dyad provided turn-key implementation of noise controls, from material procurement to installation. Installation took place on off-hours  to minimize impact on production. 

                     noise, sound, loud, noisy, box plant, paper, converting, OSHA, PEL, loud 

 Percent of Employees with Exposures Above 90 dB 
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  • 90% of employee exposures were brought into compliance.
  • Average sound energy levels were reduced by  half.
  • Dyad went on to treat two more  plants owned by the company.
  • Overall cost was less than a third of the budget.

October 17, 2013  by
Noise Linked to Heart Health Risk

noise, loud, airport, heart health, airplane, osha, hearing, sound
Image credit: freedigitalphotos.net

A recent study has linked a 10 decibel increase in noise to a 3.5% increase in heart-related hospitalization (heart failure, heart rhythm disturbances, cerebrovascular events, ischemic heart disease or peripheral vascular disease). This study looked at airport-related noise among populations 65 years and older who are on average exposed to between 45 and 55 decibels. 55 decibels is more quiet than what one would expect to be exposed to during a typical conversation.

The Occupational Safety and Health Administration (OSHA) sets an action level at 85 decibels based on hearing conservation criteria. Sound levels of 85 decibels are often seen in industry, food service settings, school gymnasiums and cafeterias. Although the government says that exposure to 85 decibels for 8 hours a day, 40 hours a week should not damage your hearing, imagine what it might be doing to your heart.



September 25, 2013  by
Case Study: The Noisy Restaurant

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The Issue

A recently renovated cafe was uncomfortably loud when occupied. Employees reported needing to shout in order to be heard and received regular complaints from customers. Surfaces within the restaurant were generally acoustically ‘hard’; sheetrock walls and ceiling, bare wood floors, many windows and mirrors. The owner wished to preserve existing aesthetic as much as possible.


DYAD collected 1/3 octave band sound level measurements within dining areas of the restaurant during business hours. Based on the frequency profile of the sound level measurements, it was determined that the main source of the elevated noise was indeed the occupants’ speech. Sound levels in occupied areas of the main dining room reached average levels of over 80 decibels with restaurant only about half full. To put that in perspective, the United States Occupational Safety and Health Administration (OSHA) requires employers to implement a hearing conservation program when average noise levels exceed 85 decibels.

Sound Level - Center of Main Dining Room While Occupiedsound, noise, noisy, decibel, restaurant, cafe, noise reduction, sound

DYAD also collected reverberation time measurements when the restaurant was unoccupied. Reverberation is the persistence of sound in a space after the original sound is made.  Reverberation directly contributes to the elevation of overall sound levels and affects occupants’ ability to understand speech.

Measured Reverb Time - Center of Main Dining Room – No Treatment
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Measured Reverb Time - Center of Small Dining Room – No Treatment

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Reverb measurements were found to average 0.981 seconds in the main dining room and 0.973 seconds in the smaller dining room.


The client requested that DYAD reduce noise in the larger and more heavily used dining room. Calculations were performed to determine the appropriate type of noise absorbing materials, the amount of this material and the installation locations to achieve the desired amount of noise reduction. Unlike most industrial situations, in this case there could be such a thing as too much noise reduction as it can lead to a dead feeling within a restaurant.

Based on these measurements and calculations, DYAD settled on specially accoustically tuned panels affixed directly to about two-thirds of the ceiling via a specifically formulated water-based non-toxic low odor adhesive and painted to match.


Measured reverberation time within the treated area was reduced by about 66% to an average of 0.336 seconds.

Measured Reverb Time - Main Dining Room – With Noise Reducing Treatment

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Measured Average Reverb Times Before and After Treatment


Before Treatment (sec)

After Treatment (sec)



Main Dining Area




Smaller Dining Area




While the results were mathematically significant, the real world difference was astounding, with staff and customers alike raving about the immediate and hugely positive difference and pleasing visual aesthetic. Overnight, the restaurant had been transformed from a cacophony to a gentle murmer. 

 sound, noise, noisy, decibel, restaurant, cafe, noise reduction, sound

August 26, 2013  by
Noise-Induced Hearing Loss: The Hidden Health Effects of Bartending

Too often hazardous noise exposure is something that we associate only with heavy industry. However, a recent study conducted by students at Illinois State University showed that bartenders may be exposed to noise levels well above OSHA limitations.


This study found that bar workers were exposed to noise levels generally exceeding OSHA’s hearing conservation level of 85 dBA and in some cases above OSHA’s permissible exposure limit of 90 dBA. In fact, workers at one bar had noise dosages more than two times higher than that permitted by OSHA.


Noise exposure is especially insidious in that the health effects are irreversible and undetectable until the damage has already been done. Some bartenders interviewed during this study noted that their perceived hearing acuity had suffered and that they believed themselves to be more tolerant of loud noises, symptoms suggestive of permanent hearing loss.


The authors of the study suggest that bar owners consider implementing controls to protect the hearing of their workers. Possible noise control solutions include lowering the volume of music, requiring the usage of employee hearing protection or the installation of noise absorbing materials.


Thanks to Brandon Jeralds, Logan Futris, Travis Fellers and George Byrns of Illinois State University

Noise, bartender, restaurant, hearing loss, OSHA, noise control, soundNoise, bartender, restaurant, hearing loss, OSHA, noise control, soundNoise, bartender, restaurant, hearing loss, OSHA, noise control, sound

January 24, 2011  by Dyad News
Backing Down on Work Noise - Bad News for Workers

Despite compelling evidence that workers are suffering from preventable, permanent hearing loss, the U.S. Labor Department says it's withdrawing a proposal on noise in the workplace that could have forced manufacturers to install noise-reducing equipment.   

Right now, OSHA allows employers to provide protection equipment, such as ear plugs, to guard against excessive noise in the workplace, but one government expert says it's just not enough to protect workers.  

David Michaels, the assistant secretary of labor for occupational safety and health told the Wall Street Journal, "there is sufficient evidence that hearing protection alone cannot prevent workers from suffering preventable hearing loss". He also said that "easily applied" administrative or engineering controls could be used to protect workers.  He went on to say hearing loss caused by excessive noise remains a "serious" workplace problem. Since 2004, nearly 125,000 workers have suffered significant, permanent hearing loss.

An agency spokesperson said OSHA believes the proposed new regulations wouldn't have imposed overly burdensome costs on businesses. 

November 10, 2010  by Dyad
High Noise Can Affect Job Performance

When thinking about dangerous noise in the workplace, it’s natural to focus on the substantial health effects, but there is also the potential effect on job performance to consider.

According to the American Industrial Hygiene Association, studies show that the effects on job performance can be significant.   

Noise levels as low as 80 to 85 dB can affect performance.  More complex tasks can be compromised at noise levels of 95 dB and above.  Above 130 to 140 dB, visual and motor skills can be reduced in the performance of simple tasks.  Task performance is more likely to be degraded when people perceive they have no control over the noise, especially when the noise comes in unpredictable bursts. 

It’s not just about task performance.  Excessive noise can have social and emotional effects on workers. Once the noise stops, the adverse effects can go on in the form of:  frustration; anxiety; increased risk of antisocial behavior; decreased helpful behavior.

The indisputable solution is noise abatement.  Once a company has initiated a hearing conservation program, many of the negative effects on job performance are reversed. 

Companies employing noise control also report fewer accidents and absences.

November 2, 2010  by admin
Study Shows Workplace Noise Can Lead to Heart Disease

Heart disease
A study released this week connects noisy work places to heart disease in many employees. The study released by researchers at the University of British Columbia in Vancouver shows that workplace noise can, and does have a significant impact on employee health; especially heart disease. Previously employers though occupational noise likely only lead to hearing problems; it seems they now have more problems to deal with as well.

© 2013 Dyad LLC           5 Centerpointe, Suite 400 Lake Oswego, OR 97035           (503) 387.3162           info@dyadnoise.com