Employers Can Protect their Workforce from Noise-Induced Hearing Loss

How to build the foundation to protect workers against hearing impairments.

• By Tim Turney
• Jun 01, 2021

22 million workers are exposed to hazardous occupational noise each year, a figure nearly equivalent to the population of Florida. Prolonged exposure to excessive noise levels can cause life-changing damage because the harm to the sensory cells and other structures within the ears is irreversible, resulting in permanent noise-induced hearing loss (NIHL).

NIHL is the third most common chronic health condition in the U.S., affecting one in four adults. It results in injuries that can seriously impair a worker’s quality of life. Employers, meanwhile, run the risk of reduced productivity, rising costs due to sickness days, increased costs for training and recruitment and catastrophic penalties and compensation claims. OSHA estimates that employers spend $242 million annually on workers’ compensation for hearing loss disability.

NIHL damage is, however, as preventable as it is permanent. Workers can wear hearing protection such as earplugs and earmuffs, but the greatest way to reduce hearing loss is by identifying and avoiding excessive noise in the first place. Research has shown that monitoring noise levels has a significant effect on occupational NIHL and can determine whether an operative is at risk of occupational hearing loss before it is too late.

Understanding the Legal Limits on Noise Exposure

The risk of noise damage occurring depends on the intensity of the noise, distance from the noise source and exposure duration. Consequently, OSHA sets the legal limits on noise exposure in the workplace based on a worker’s time-weighted average over an eight-hour day. OSHA’s maximum permissible exposure limit to noise is 90 dBA (decibels) for all workers. For example, under the OSHA guidelines, a person should not expose him or herself to the sound of a lawnmower that produces around 90 dBA for more than eight hours, even with hearing protection.

Conversely, the National Institute for Occupational Safety and Health (NIOSH) recommends that all worker exposure to noise should be controlled below or equivalent to the level 85 dBA for eight hours, a decibel level comparable to the sound of a passing diesel truck. NIOSH designed its recommendations to represent the best scientific practice concerning noise exposure. On the other hand, the OSHA exposure limit is the minimum legal requirement that must be complied with.

In 1981, OSHA introduced a new regulation requiring employers to implement a hearing conservation program for workers that are exposed to an average noise level of 85 dBA or higher for an eight-hour shift. Hearing Conservation Programs require employers to measure noise levels, provide free annual hearing exams and hearing protection, offer training, and conduct evaluations of the adequacy of the hearing protectors in use. The programs cost around $350 per worker each year, necessitating $70,000 annually for a 200-strong workforce. They are mandatory until the employer makes sufficient changes to the tools, equipment and schedules used so that conditions are improved, and worker exposure is demonstrated to be less than the 85 dBA.

Types of Noise Measurements and Sound Monitoring Applications

Measurement of sound or unwanted sound (noise) encompasses a vast range of decibel levels and many diverse applications. The goal of measurement is to assess an individual’s eight-hour exposure, so the noise monitoring process itself may be a quick measurement using a sound level meter if the noise is steady throughout the day. Alternatively, a more comprehensive use of multiple noise dosimeters on many people over several days may be required, depending on the variation in exposure and number of employees.

Using Noise Monitoring to Gather Accurate Insights

Noise monitoring provides accurate insights into the noise levels of your working environment, allowing you to identify problem areas and ensure you adhere to OSHA regulations. With the right equipment, trained health and safety managers, using either a sound level meter or a dosimeter, can carry out a successful noise-monitoring program on-site. However, with various monitoring devices on the market, it can be difficult to identify the most suitable product for your unique working environment and ascertain how much staff training is required. Ideally, those responsible for the task should understand noise in terms of measuring terminology, frequency and amplitude (deciBels). In addition, the individual will need to know what legislative actions are required at different exposure levels and how a variety of instruments can monitor noise, from sound level meters to dosimeters and which is best for the working environment in question. Once the individual understands the basics, they will need to know how to turn readings from noise monitors and dosimeters into values that can help determine the most appropriate form of hearing protection and understand how to reduce exposure though a variety of means, such as reducing the exposure time of controllable noise at the source.

Trained professionals should also recognize that noise measurements should be repeated if there are changes to the workplace layout, installation of additional machinery or a change in the type or distribution of work undertaken. Of course, individuals may not be knowledgeable about all the aspects covered above and all the detail involved, so external consultation should be sought for areas where competency may be lacking.

How and When to Use a Sound Level Meter

A sound level meter is a hand-held device, enabling measurements to be taken at the ear with the instrument pointing at the noise source. This process must be repeated for both ears, for all duties employees perform, making it possible to calculate an accurate record of daily exposure. Settings on these meters can be adjusted in line with legislation.

When using a sound level meter, measurements must be started at the beginning of a task, representing workers’ actual exposure. If workers are likely to be exposed to high levels of impulsive noise, emitted from heavy pressing operations or sheet metal working, peak noises must be measured for accurate results and compared to peak action levels.

A sound level meter is the ideal solution if you need to know the overall noise level of a task, piece of machinery or area.

How and When to Use a Dosimeter

Dosimeters are best for personal noise measurements where it is difficult or unsafe to get close to employees with a sound-level meter because dosimeters are smaller and body-mounted. For example, a dosimeter would be ideal for forklift truck drivers exposed to many different noise levels and irregular working patterns.

Employees can wear dosimeters for their entire working shift. Data is logged instantly, and when downloaded onto another device, offers insights into daily exposure and peak levels. However, it is important that the data is presented in a format that is easy to understand to a layperson who may not be familiar with all acoustic terminology. Therefore, choosing a dosimeter with accessible software is essential to ensuring accurate insights are gained and, ultimately, taken on board.

Workers can also make a diary of times and jobs performed, allowing the employer to see the operations that require more effective noise controls. Dosimeters can be moved to different employees as long as the measurements taken for each employee are representative of their working day. Most modern dosimeters will also project the noise dose forward to the standard eight-hours so that no manual calculations are needed.

However, noise dosimeter measurements are subject to tampering, so spot-checking high levels with a sound level meter is beneficial to ensure accuracy. Therefore, when choosing between either monitoring solution, it should be noted that a combination of both solutions can provide the most valid measures.

Protecting Your Future Workforce Through Noise Monitoring

NIHL is more common than diabetes or cancer. Employers have a responsibility to prevent damage to their workers’ health and to up-skill their workforce, so they realize the implications of damaging noise exposure. Monitoring solutions are an ideal solution for you and your organization to achieve compliance with legislation and protection for your workforce effectively and demonstrably. Skill and knowledge of measuring noise can take years to build, so the information above can only be considered a foundational introduction. If certain aspects of noise monitoring and control are outside of an individual’s competencies then external consultancies, training and support can be sought to bridge knowledge gaps and ensure employees get the critical protection they need.

This article originally appeared in the June 1, 2021 issue of Occupational Health & Safety.