Noise is one of the most pervasive occupational health problems in industry. While many companies have been successful in combating their noise problems and preserving their employees' hearing through hearing conservation programs, experts say some employers are putting too much emphasis on elements such as hearing testing and not enough where it is really needed: noise control and training. We asked several experts to explain the proper components of a hearing conservation program and to give advice about how to fine-tune existing programs for improved performance.
OSHA's noise regulation, enacted in 1972, limited noise exposure to 90 decibels (dB) for eight hours of exposure per day. In 1983, OSHA amended its original regulation to incorporate a lower protective level and to define hearing conservation programs. The revision called for noise monitoring and protective equipment in an 85-decibel environment. Above this level, employers are required "to implement a continuing and effective" occupational hearing conservation program (OHCP).
Mary McDaniel, MS-CCCA, president of Pacific Hearing Conservation in Seattle, said that if an employer has reason to believe hazardous noise exists, it is the employer's responsibility to implement a program. "If, for example, you own a carpentry shop where there are table saws and planers that emit great noise, then you have reasonable information to believe your workplace has hazardous noise," said McDaniel.
Behavioral signs are another way for employers to determine if a program is needed. Don Gasaway, a hearing conservation specialist with Aearo Corp., said if an employee has to move from a normal voice to a loud voice when he speaks in a workplace, above 82-85 dB, hazardous noise probably exists. "If employees are having difficulty being heard by a companion at arms' length, then a program is needed," said Gasaway.
OSHA's 1983 amendment said that hearing conservation programs must include noise monitoring, ear protection, education and training, audiometric testing and review and record keeping. Many hearing conservation professionals believe there are five basic elements to a successful program:
- Annual audiometric testing.
- Noise measurement and control.
- Hearing protection.
- Training and enforcement.
- Follow-up and evaluation.
Identifying Hearing Loss
Experts say occupational hearing loss is easy to ignore because of a lack of physical signs. "The ears don't bleed, there is no pain, and there is no apparent physical deformity to the ear, so people don't even know a problem exists," said Tom Thunder, audiologist with Acoustic Associates in Palatine, Ill.
The type of hearing loss associated with workplace exposure is called sensory-neural. It is damage to a very sensitive part of the hearing system called the cochlea, which is a receptor organ for hearing in the inner ear that converts sound waves into electrical impulses sent up to higher auditory centers. There are 16,500 tiny hair cells in each cochlea that differentiate between sounds of different pitch and which can be damaged by loud noise.
Hearing loss is a slow, progressive process that may not be noticed for many years by workers who have been exposed to loud noise. "The ability to piece things together to hear only what one needs to hear increases with age. An employee who has worked in a factory for 25 years only needs to hear what he needs to do his job," said Gasaway.
Despite the insidious nature of the disability, there are subtle clues that become noticeable when someone is experiencing sensory-neural hearing loss. "Voices are not as clear, and when someone speaks, it sounds like he is talking in a barrel," said Gasaway.
Other clues include ringing, buzzing or chirping in the ears after leaving a noisy situation; asking for repeats in conversation; not hearing well on the phone; and difficulty hearing speech in the presence of background noise.
Annual audiometric testing can help employers identify whether their employees are suffering from hearing loss. McDaniel said it is best to have employees tested when they begin employment.
The first part of audiometric testing includes a baseline audiogram, which establishes the threshold or softest levels of noise an employee can hear. Subsequent audiograms are compared with the baseline audiogram to monitor changes in the employee's hearing.
Rena Glaser, audiologist and manager of medical surveillance for 3M's Corporate Occupational Medicine Department, St. Paul, Minn., said 3M employees are tested as soon as they are hired. "We try to get the employees preplacement, especially if they are going into a production area," said Glaser.
Audiograms can be useful in tracking employees' hearing loss, but McDaniel cautioned that employers should not make hearing tests the focus of their program. Rather, the tests should simply be used as a measuring tool. "An annual audiogram is not the end-all-be-all of a hearing conservation program. It doesn't protect or save anyone's hearing," said McDaniel.
Conducting a noise hazard analysis, which includes noise measurement and possible solutions to controlling noise, is the first step to preventing employee exposure. "Understanding the noise risks involved in the workplace through identifying the sources of noise really feeds the whole hearing conservation program," said Lee Hager, incoming president of the National Hearing Conservation Association (NHCA).
Checking the decibel levels in a workplace through monitoring equipment, such as noise dosimeters and sound level meters, is the best way to track and measure noise.
Instituting engineering controls can eliminate or reduce noise levels at the source. Possible engineering controls include maintenance of machinery to eliminate excessive noise, isolators for noisy equipment, noise baffles or equipment enclosures, or placement of noisy machinery in areas of the facility that are away from employees.
McDaniel said companies are too concerned with the other aspects of their programs and as a result, don't put enough emphasis on the noise control portion of their programs. "Things have gotten a little lax in the noise control department. Employers would be better served to reduce the noise exposure through engineering controls," said McDaniel.
If engineering controls are unsuccessful, then employers need to provide hearing protection. When used properly, experts agreed that hearing protectors can be a very effective part of an OHCP. "The difficulty is not in the protector itself, but in the administrative program that surrounds the protector," said NHCA's Hager.
Appropriate selection, use and fit of the protectors are common program glitches. There are many different types of protectors on the market today. When deciding which type is best, employers should look at the type of noise exposure present and the level of hearing ability their employees need, and assess the employees' need to communicate in their environment.
At 3M, individual plants are responsible for hearing protection, but Glaser said her department suggests that safety management conduct annual fit tests.
"Fit is very important. If the protector doesn't fit, isn't comfortable and the wearer isn't able to use it, it doesn't do any good," said McDaniel.
Ironically, workers who wear hearing protectors still have hearing loss. Experts attribute this to the employer's tendency to overprotect employees. At times, management often selects a hearing protector because it has the highest noise reduction rating (NRR).
"If an employee is working in an area where he only needs 6 or 8 dB of protection, and he uses a protector that provides 25-30 dB of protection, that is a little bit of overkill," said McDaniel.
Consequently, if an employee can't hear because he is overprotected, he will likely take out the protectors. "In reality, those employees with greater protection are experiencing more hearing loss, and those with less protection have totally effective noise reduction," said Gasaway.
Another problem regarding protectors is that those charged with selecting the protectors have too many options. "Don't play the numbers game when it comes to buying a protector, said Thunder. "Asking for the protector that works against the highest level of noise may not necessarily protect your employees the best." To ensure proper selection, have an educated selector make decisions about protectors.
Training is Key
OHCP programs often fail, not because of the wrong type of hearing protector, but because of the lack of employee training and education. Properly training your employees on how to use hearing protection and educating them on the dangers of hazardous noise is the most beneficial way to prevent hearing loss. "Over my 43 year career in hearing conservation, I have found that the most effective programs are those with hands-on training," said Gasaway.
Hands-on training could mean the difference between having your employees protected because they know how to insert their protectors or having them exposed to high levels of noise because they don't. Gasaway suggested leading employees through an examination of their ears in training seminars. For example, he said, employees should understand that, to have an ear plug provide a proper seal, the rear end of the plug should be a half-inch beyond the dip in the outer ear.
How can employers encourage their employees to wear hearing protection? The more education employees receive, the more motivated they will be to wear the protectors. "If the worker is made aware of the hazards and what the effects of noise exposure will be, he will want to know what he can do to protect against it," said McDaniel.
Acoustic Associates' Thunder believes that audio and visual demonstrations are the most powerful ways to get employees to understand the consequences of noise exposure.
When he conducts training sessions, he uses hearing loss simulation tapes. These audio tapes contain unfair hearing tests. The tape gives employees 10 words heard through an impaired ear, then asks them to guess what those words are. "The words at this point are almost indistinguishable," said Thunder. Then the same 10 words are heard through an ear with mild hearing loss. Employees are able to distinguish the sounds a little more clearly. Finally, they hear the words through an ear with clear hearing. "Employees realize what the words are and they are extremely surprised to know that what they thought they heard through the impaired ear was nothing like the actual word heard through the perfectly good ear," said Thunder.
Because hearing loss doesn't have any recognizable physical signs, it is dramatic to see what the inside of a damaged ear looks like. When Thunder conducts the visual portion of his training program, he shows employees a picture of the cochlea of the ear in perfect condition. Then he shows a picture of what happens when the cochlea is damaged from 30 years of noise exposure. The hair cells in the damaged cochlea are flattened, and there is debris in the ear. "This is a very effective image because employees see what happens. Once these cells are gone, they can't be regrown. No amount of Rogaine can help with this damage," said Thunder.
Even after the training seminars and audiometric testing are finished, employers need to keep employees diligent about protecting their hearing. Thunder said monitoring your employees' use of their hearing protectors on a daily basis is as important as demonstrations and training seminars. "Simply training your employees doesn't mean that when you send them back to work with the protectors, they will wear them," said Thunder.