May is Better Hearing and Speech Month: For 45 Years NIOSH Helps Prevent Occupational Hearing Loss

Back in 1927, when an organization then known as the American Society for the Study of Disorders of Speech* first promoted May as “Better Hearing and Speech Month,” very little was known about occupational noise-induced hearing loss. But for more than 45 years, NIOSH has been researching ways to prevent it. Occupational hearing loss (OHL) is one of the most common work-related illnesses in the United States. Each year, about 22 million U.S. workers are exposed to hazardous noise levels at work. OHL is permanent and has a personal, social, and economic price. It is also nearly always preventable.

As we celebrate Better Hearing and Speech month, let’s take a look at the efforts NIOSH has made towards hearing loss prevention. While we think about what has been accomplished, let’s be inspired to keep the momentum going until no worker sustains a hearing loss just from doing his/her job.

Establishing Occupational Exposure Limits

Noise was among the first seven criteria documents which NIOSH published in the year following its establishment. The 1972 document recommended an immediate exposure limit of 90 dBA averaged over an eight-hour workshift, with “new installations” required to meet an exposure limit of 85 dBA and all workplaces required to meet the lower limit pending a feasibility study.  The recommendation allowed exposures to increase by 5 dB for every halving of exposure time (called an “exchange rate”).  The criteria document also detailed methods for protecting workers exposed to noise levels in excess of these limits – methods which have collectively come to be called “hearing conservation programs.”  In 1998, NIOSH published an updated criteria document which established the recommended exposure limit (REL) at 85 dBA for all workplaces, reduced the exchange rate to 3 dB, and shifted the emphasis from “hearing conservation” to “hearing loss prevention.”

Setting an Agenda for Hearing Loss Prevention Research

As indicated by the release of a noise criteria document so soon after its establishment, NIOSH has always considered occupational hearing loss among its top priorities. As NIOSH approached its twentieth anniversary, it sought expert input regarding its research priorities; hearing loss made the list of the NIOSH leading work-related diseases and injuries (https://www.cdc.gov/niosh/docs/89-135/). Later, NIOSH expanded from focusing on its own research priorities to establishing an occupational research agenda for the entire nation.  Hearing loss was included as one of 21 focus areas of the 1996 National Occupational Research Agenda (NORA).  As NORA evolved to have a sector focus, OHL continued to be represented as a cross-sector program. Today, NIOSH has targeted research efforts to protect against hearing loss in areas such as construction, manufacturing, mining, and services sectors.

Conducting Surveillance and Understanding Risk

Knowing who is at risk is the first step in preventing hearing loss. NIOSH has been involved in many national survey efforts to collect data on noise exposure, hearing levels, and hearing loss prevention activities.  Early on, NIOSH conducted its own national surveys on noise exposure and hearing conservation programs; in recent years, NIOSH has worked to include measures of occupational noise and hearing loss in broader national surveys such as the National Health and Nutrition Examination Survey and the National Health Interview Survey. In 2009, NIOSH started a national surveillance system for OHL by collecting de-identified hearing test results of noise-exposed workers through partnerships with audiometric service providers and employers who do this testing as part of mandated hearing conservation programs. This approach has allowed NIOSH look at the risk of OHL in different sectors and across time, so that interventions can be targeted effectively.

Improving Impulse Noise Measurements

Impulsive noises are particularly harmful to the ear, and the NIOSH criteria document establishes special limits for this kind of noise. However, NIOSH discovered that many sound measurement instruments were not always capable of correctly capturing and characterizing exposure to these types of sounds. As a result, NIOSH developed and patented new instrumentation for measuring impulsive sounds and is currently working to update occupational guidelines on exposure to impulse noise. Among the workers exposed to impulsive sounds are the 1.2 million federal, state, and local law enforcement officers who must train regularly with firearms and are often exposed to very high impulse noise levels (sometimes in excess of 170 dB SPL). NIOSH published special guidelines for occupational firearms exposure in the NIOSH Alert: Preventing Occupational Exposures to Lead and Noise at Indoor Firing Ranges and in two Workplace Solutions documents targeting exposures at indoor and outdoor firing ranges.

Encouraging the Purchase of Quieter Tools and Machinery – Buy Quiet

Whenever it is technically feasible, the best solution to dangerous noise levels in the workplace is to reduce the source of the noise. One way to do this is to develop a plan to take noise levels into consideration when making purchasing decisions. NIOSH launched a Buy Quiet initiative to help employers establish their own Buy Quiet programs. Guidelines and other resources such as posters, infographics, and a database of power tool noise levels are available on the NIOSH Buy Quiet topic page.

Measuring How Well Earplugs Work – Fit-testing

If noise cannot be reduced to a safe level, then workers must use hearing protection devices (HPDs). If HPDs are properly selected and correctly worn, the devices will minimize the chances of developing a hearing loss. But how can a person tell if their HPDs are fit correctly? Hearing protector fit-testing is the answer.  In recent years, the number of commercially-available fit-testing systems has gradually increased.  NIOSH developed HPD Well-Fit™  to provide a system that can quickly and inexpensively test the performance of any type of earplug. Fit-testing technology is a huge advancement in efforts to save workers’ hearing. NIOSH also developed QuickFitWeb as a fast screening tool to check whether a hearing protector is providing at least 15 dB of sound reduction.

Evaluating Intervention Effectiveness

NIOSH is committed to promoting evidence-based recommendations. NIOSH holds a seat on the advisory and editorial boards of the Cochrane Work Review Group, one of the many groups in the Cochrane collaboration, which evaluates available evidence on a given topic through systematic reviews. NIOSH researchers contributed to the group’s systematic review of interventions to control noise and promote hearing loss prevention. Based on the few available well-controlled studies, the review concluded that stricter regulation can be effective in reducing occupational noise, the effectiveness of hearing protection is highly dependent on training and proper use, and workplace hearing conservation programs need to be better implemented. Cochrane Work is in the process of updating this review to include any additional recent studies; watch for the new version in the next few months.

Awarding Excellence in Hearing Loss Prevention

In another effort to obtain information on interventions that work towards hearing loss prevention, NIOSH partnered with the National Hearing Conservation Association (NHCA) to create the Safe-In-Sound Excellence in Hearing Loss Prevention Award™. The award recognizes organizations that document measurable achievements in hearing loss prevention and disseminates information on their real-world successes. The Safe-in-Sound Award™ process has resulted in the acquisition of high-quality field data related to noise exposure monitoring and successful noise control outcomes. Since 2009, awards are presented annually at the NHCA annual conference by the NIOSH director or his or her representative. Read about recent winners and their impact here. The call for nominations is happening now! Apply by July 15, 2017.

Communicating Findings and Moving Research and Innovation into Practice

NIOSH has grown increasingly aware of the need to disseminate research findings and recommendations through new media channels in addition to the traditional outlets of scientific presentations and journal publications. In order to reach out directly to employers, workers, service providers, professional organizations, and others, information is tweeted regularly from @NIOSHNoise and posted to Facebook, YouTube, and other social media through the main NIOSH channels. In addition, we have published blogs on topics ranging from sound-measuring apps to program evaluation checklists to noise from stock car racing, vuvuzelas, and even music – check out all of them here.

Noise exposure crosses all industries and affects many workers. Since its inception, NIOSH has worked to help employers reduce dangerous noise levels and prevent hearing loss. With so many people still exposed to hazardous noise and occupational hearing loss still so prevalent, though, we still have much to do.  We would love to hear from you in the comment section below about if/how you have used our research, and areas you would like to see us focus on in the future. Let’s make work a quieter, safer place together.

For additional information, follow NIOSH Noise and Hearing Loss research on Twitter at @NIOSHNoise and visit the noise topic page.

Trudi McCleery, MPH,  and the  NIOSH Hearing Loss Prevention Team, Division of Applied Research and Technology, NIOSH.

*The name of the organization has changed several times over the years. Since 1978, it has been called the American Speech-Language-Hearing Association (ASHA).