Our sense of hearing is at the core of how we communicate and experience the world, how we stay aware of our surroundings and thus, remain safe. When hearing loss becomes an all-too-common reality and has long-term and irreversible impacts on individuals, organizations must step in and take preventative action.
Hearing loss prevention is at the core of the Hearing Conservation Program. The different steps of the program are measure, evaluate, fit, standardize, control, motivate and evaluate .
The causes of hearing loss and noise-induced hearing loss (NIHL)
According to the World Health Organization (WHO), over 5% of the world’s population suffers from disabling hearing loss, which can range from difficulty in hearing conversational speech to deafness. It is influenced by factors beyond our control like genetics, diseases and medicines, and aging, but also by a factor well within our control – excessive exposure to loud noise.
Noise-induced hearing loss (NIHL) is the most common preventable occupational injury. To be considered as NIHL, it must include these characteristics: permanent and progressive, bilateral (affects both ears), painless, invisible trauma, unnoticeable in the early stage and cumulative with each over-exposure.
The yearly global economic impact of NIHL for businesses is estimated at US$750 billion and growing since hearing loss in the workplace also increases the risk of accidental injuries (workers with hearing troubles are twice as likely to experience an accidental injury than those with good hearing).
NIHL occurs across a wide spectrum of industries, but workers in some of them are more exposed to dangerous levels of noise. These industries include agriculture, mining, construction, manufacturing, utilities, transportation and the military.
If you observe any of the signs of noise issues in your workplace below, it is time to measure environmental noise.
Ringing or humming in the employees’ ears after exposure to loud sounds.
Impeded communications (employees must shout to be heard by a coworker at arm’s length).
Temporary loss of hearing after leaving work.
STEP 1: MEASURE
Monitoring noise exposure is the first step in hearing loss prevention. According to OSHA standards, a hearing conservation program is required “whenever employee noise exposures equal or exceed an 8-hour time-weighted average sound level of 85 decibels measured on the A scale or, equivalently, a dose of fifty percent”.
Employers are required to monitor all employees whose noise exposure exceeds 85 dB in 8 hours, including all continuous, intermittent and impulsive noise between 80 and 130 dB.
There are two commonly used methods of monitoring noise levels:
Area sampling using a sound level meter: an instantaneous or continuous noise level reading in a specific area over a specific period. It is only accurate when the noise levels are constant.
Personal sampling with a noise dosimeter (personal sound exposure monitor): a dosimeter microphone is attached to the worker near the ear and continuously measures the incoming noise over a certain sampling period. The read-out shows the average equivalent noise for that sampling period.
Both methods measure the unprotected exposure; an estimate of the protected exposure must be made using the noise attenuation rating of the hearing protector. Since there is no way to tell how much protection an individual worker is receiving from their hearing protector, such an estimate is merely a guess.
The best method is to directly measure the individual’s protected exposure with in-ear exposure monitoring.
In-ear exposure monitoring measures and records the worker's actual protected noise exposure, over their entire work shift. This technology provides real-time monitoring throughout the workday and alerts the worker when the noise dose approaches or exceeds safe limits.
STEP 2: EVALUATE
The assessment of hearing loss also requires a review of audiograms, the hearing protection data and the clinical history of a worker. Audiograms are a common way to evaluate workers’ hearing sensitivity over time. These tests, performed within the first six months of an employee’s first exposure to noise (baseline audiograms), and annually thereafter, constitute a record of the worker’s hearing thresholds over time at various frequencies.
A threshold between 0 and 25 dBHL is considered the normal range for an adult.
Mild hearing loss happens from 25 to 40 dBHL
Moderate hearing loss from 40 to 55 dBHL
Moderate to severe from 55 to 70 dBHL
Severe hearing loss from 70 to 90 dBHL
Profound hearing loss at 90 dBHL or higher
According to regulations, audiograms and their results must be made available to all employees and at no cost. They also need to be archived for the duration of employment and a program follow-up should mention if a referral is required for further testing.
STEP 3: FIT
An HCP requires a recording of the effectiveness of the Hearing Protection Devices (HPD). Fit testing provides a real-world metric to determine if employees are receiving optimal protection for their noise environment, requiring additional training or needing a different model of HPD.
Earplug testing benefits safety managers as well as employees. For managers, it fulfills regulatory requirements for training and documentation. For employees, it showcases the importance of proper protection in the workplace, helps them select and compare protectors to find the best choice for their ears and specific applications, while providing feedback on what a proper fit looks and feels like.
STEP 4: STANDARDIZE
The American National Standards Institute (ANSI) promulgates consensus standards used to inform about regulations. In the OSHA Hearing Conservation Amendment, ANSI standards are cited for calibrating audiometers used in annual testing, and for sound level meters used in noise monitoring.
OSHA issues specific regulations for recordkeeping and general industry, including methods for estimating the adequacy of hearing protector attenuation and acoustic calibration of audiometers.
STEP 5: CONTROL
Engineering and administrative controls are the first actions taken when noise exposures exceed mandated levels. Engineering controls reduce sound exposure by modifying or replacing equipment or making physical changes at the noise source or the transmission path. Administrative controls include such actions as giving noise-exposed employees break time in quiet areas, or rotating employees among noisy and quiet workspaces, as to safeguard them from long exposures to noise.
Sometimes, administrative and engineering controls alone are effective in reducing noise and solving the problem. If administrative and engineering controls are not feasible, practical, or sufficient to reduce workplace noise to acceptable levels, the employer must fit employees with the appropriate hearing protection. At least one type of earplug and one type of earmuff are to be available to workers.
Finding the right hearing protection
There are a few key aspects to consider when choosing the right HPD.
The environment. Climate influences the selection of HPDs – earmuffs are generally more suitable in colder climates, for instance. The type of work being performed should also be considered: Is communication required or the noise intermittent, causing frequent donning and removal of hearing protection? Do the workers handle materials that are dusty, oily, corrosive, or caustic? Is the detectability of foreign material necessary in the process? What other PPE is required to be worn with the hearing protection?
The Noise Reduction Rating (NRR) is an estimate of the average sound level reduction or attenuation provided by an HPD in a laboratory environment. It is not an accurate predictor of an individual’s protection from noise exposure.
The user’s Personal Attenuation Rating (PAR) from individual fit testing. The PAR is an actual attenuation value measured for an individual earplug fitting. HPD fit testing is an OSHA best practice and is currently the only way to know how much attenuation an individual worker is capable of receiving from his or her hearing protection.
Ease-of-fit and in-ear comfort for workers. This has a heavy impact on the effectiveness of an HPD. If the hearing protector is not comfortable, it is less likely to be worn—or worn correctly—and provide the noise reduction it was designed to offer.
Types of earplugs
Earplugs provide an airtight seal of the ear canal. They come with different attenuation ratings (NRRs) for different noise levels. They can be either disposable or reusable.
Foam earplugs are affordable, effective and easy to use. They conform to the shape of the ear canal and change shape dynamically to accommodate jaw movement from chewing, talking, etc. That is what makes them particularly effective and one of the reasons they provide the highest attenuation of any HPDs.
Banded earplugs are connected by a flexible band and are suitable for people who move in and out of noisy areas. They are worn under the chin and can be easily stored around the neck when not in use.
Detectable earplugs are designed for high-visibility and detectability by a variety of methods in processing environments where foreign material contamination must be avoided.
Regardless of the material, earplugs are most effective when the wearer has been properly trained in the use and insertion.
Types of earmuffs
Made from rigid cups with soft cushions that seal around the ear, earmuffs come in a variety of shapes and sizes. Three common designs include over-the-head, cap mounted and behind-the-neck.
To block noise effectively, a tight seal between the ear cushion and the head is critical. Gaps provide an easy path for sound to bypass the ear cups, thus reducing the amount of attenuation provided by the earmuffs.
Why choose an earmuff over an earplug?
It’s easier to achieve proper fit with an earmuff, but earplugs typically provide higher noise reduction when used correctly, although obtaining the correct deep insertion of an earplug is more challenging. Other advantages of earmuffs include convenient wearing during exposure to intermittent noise and more warmth in cold environments. Earmuffs can also be worn with hearing aids and are longer lasting. However, comparatively, earmuffs may become uncomfortable when used for longer periods of time and be incompatible with other PPE such as hard hats or eyewear.
In some situations, PPE needs to preserve situational awareness and remain communication-friendly, preserving speech while protecting hearing.
STEP 6: MOTIVATE
The best hearing protection devices have no value if they are not worn or worn incorrectly.
The best incentive for workers to use HPDs or to wear them correctly is if they understand the long-term implications of NIHL. Discuss with employees the effects of NIHL and explain the results of their annual audiograms and the results. Publish information on noise, noise levels and implications on the sense of hearing.
Offer training to make sure that the HPDs are well fitted and correspond to the work environment.
Reward workers who comply and support their colleagues
One-on-one trainings are also effective in educating workers on how to use and maintain PPE.
STEP 7: EVALUATE
To make sure that the Hearing Conservation Program is working, the last step is to evaluate the performance – by asking feedback from the employees, and reviewing the records and responsibilities.