Hearing Conservation!
Hearing loss due to noise in the workplace is often underrated as an occupational hazard.
It normally develops over a long period of time and is not visible like an injury or illness would be. The extent of damage depends on the length of the exposure and the intensity of the noise.
Various kinds of hearing protection devices (HPDs) are available for use in the workplace.
The selection depends on several different factors: The noise hazard - What levels of noise are you dealing with? Frequency of noise - Is the noise pitched high or low? Fit and comfort - Does the HPD fit comfortably? Noise reduction rating or NRR - Is the NRR set at the proper level?
Permissible Exposure Levels.
There are maximum exposure times for different decibel levels. For example, if you are running a chainsaw and working without hearing protection, you can only use that chainsaw for 2 hours per workday
Indications that Noise Exposure is High
An employer needs to monitor only if the noise level achieves or exceeds 85 dBA. But how does an employer know if that is the case? Here are some factors which suggest that noise exposure in the workplace may be high enough for monitoring: Employees complain about the loudness of noise Signs that employees are losing their hearing Noisy conditions which make normal conversation difficult.
Annual Audiogram
A new audiogram needs to be obtained at least annually for each employee exposed at or above an 8-hour time-weighted average of 85 decibels. Evaluation The annual audiogram should be compared to the baseline audiogram to determine if the audiogram is valid and if a standard threshold shift has occurred. If the annual audiogram shows that the employee has suffered a standard threshold shift, a retest may be conducted within 30 days and these results can be used for the annual audiogram. Problem audiograms should be reviewed by an audiologist, otolaryngologist, or physician to determine if there is a need for further evaluation.
Measuring Hearing Loss The audiogram that results from the audiometric test will show hearing loss. The test is looking for a standard threshold shift, which would indicate hearing loss has occurred since the last audiometric test.
A standard threshold shift suggests three possible problems: The employee is not wearing or using their hearing protection properly The employee has the wrong type of hearing protection There's been a change in the workplace noise that requires new hearing protection.
Audiometer and Audiogram
A trained technician uses an audiometer to send tones through headphones being worn by an individual undergoing testing. This individual indicates when they first hear the tone and this is charted on an audiogram.
2. Earplugs
Also known as aurals. Fit in the ear canal. Come in three forms:
4. Earmuffs
Also known as circumaurals Fit over the whole ear to seal out noise Made up of three parts: cups, cushions, and a headband Available in many styles Most effective for use with impulse noise that is frequent and intermittent because they are easily removed Can be cleaned using warm, soapy water.
3. Canal Caps
Also known as superaurals Seal the external edge of the ear canal to reduce noise entering the ear Made of a soft, rubber-like substance held in place by a headband Used for intermittent noise exposure and narrow-band low frequency noise Clean by using warm soapy water.
audiogram
An audiogram is a pictorial representation of your ability to hear. A baseline audiogram is used to see changes in hearing ability over time. Later audiograms are compared to the baseline audiogram. The baseline audiogram should be completed within six months of an employee's exposure to noise at or above the action level. For at least fourteen hours before the audiogram, the employee should be protected from noise. This includes both workplace noise and non-occupational noise. Hearing protection can be used to limit noise exposure.
Recordkeeping Requirements The employer with a hearing conservation program must be able to provide OSHA all the related records of employee training and education programs.
An employer must provide records of: The preceding two years of noise exposure measurements Audiometric tests covering the entire duration of the affected employee's employment.
Audiometric Testing
An employer needs to establish and maintain an audiometric testing program if employee noise exposure is at or above the action level. Audiometric tests must be provided at no cost to the employees, and need to be performed by a licensed or certified audiologist, otolaryngologist, or other physician, or by a certified technician.
How is Noise Measured?
Basically, there are two different instruments to measure noise exposures: The sound level meter. The dosimeter.
1. Enclosure
Completely surrounds the head like a helmet. Not as comfortable as the other devices because of its size. More expensive than other alternatives. Most effective for use with impulse noise. Rarely used.
Hearing Protection Devices (HPDs) Hearing protectors filter out loud noise, but they do not block it out completely. They reduce the amount of sound reaching the delicate parts of the ear. Your employer should conduct a hazard assessment to determine what types of noise control measures should be taken. If hearing protection devices are warranted, your employer will need to provide the appropriate type.
Four categories of HPDs are available: Enclosure Earplugs (3 forms) Canal Caps Earmuffs.
The Action Level and Noise Monitoring Requirements It is not necessary for every employer to measure workplace noise. Noise monitoring or measuring must be conducted only when exposures are at or above 85 dB (known as the action level).
Factors which suggest that noise exposures in the workplace may be at this level include: Employee complaints about the loudness of noise Indications that employees are losing their hearing Noisy conditions which make normal conversation difficult. Typically, if you cannot hear someone speaking that is three feet away or less, you may need to monitor your location for noise exposure.The employer should also consider any information available regarding noise emitted from specific machines. In addition, actual workplace noise measurements can suggest whether or not a monitoring program should be initiated.
Follow-Up Procedures for the Annual Audiogram
If a comparison of the annual audiogram to the baseline audiogram indicates a standard threshold shift, the employee needs to be informed of this fact in writing, within 21 days of the determination. If a physician determines that the standard threshold shift is not work-related or aggravated by occupational noise exposure, the employer doesn't need to act. However, if the shift is work-related, the employer should: Fit affected employees with hearing protectors. Train affected employees in use and care of hearing protectors. Refit employees already using hearing protection devices with devices providing greater attenuation if necessary and retrain them in the use of this equipment.
The effects of noise in the workplace range from minor to severe. Some of the dangers from too much noise in the workplace include:
Irritability and stress from the strain of talking or trying to hear over loud sounds Inability to hear important work or safety instructions Headaches, ulcers, high blood pressure, and other disorders Temporary or permanent hearing loss.
The following rules should be remembered when inserting hearing protection ear plugs:
Make sure hands are clean before inserting earplugs. Check reusable plugs for dirt and deterioration. As you insert the earplug, lift the top of your ear with your opposite hand, to open up your ear. This provides a much more snug fit.
Equipment and Noise Levels
Many manufacturers have attempted to reduce noise output of machinery at the installation and operational level. Employers can consider purchasing machinery or equipment that meets noise specification levels. Since many workplaces accommodate a variety of noise generating equipment, manufacturers, plant operators, and workers must cooperate to reduce noise levels. However, the noise levels of some pieces of equipment cannot be reduced. Saws, punch presses, and jackhammers fall into this category, among others. If you work with tools or equipment that cannot have its noise level reduced to a safe level, you must protect yourself with proper hearing protection.
When to Monitor Again
Monitoring should be repeated whenever a change in production, process, equipment or controls increases noise exposures to the extent that: Additional employees may be exposed at or above the action level The attenuation provided by hearing protectors being used by employees may not be adequate. Affected employees must be notified of the results of the monitoring, and should be allowed to observe any noise measurements being completed.
It is possible to reduce workplace noise by using the following methods:
Moving noisy machinery to a separate area or providing a sound barrier Reducing vibration by placing machinery on rubber mounting Using sound-absorbing products such as acoustical tiles and blankets Rearranging work schedules to reduce an individual's time spent in a noisy area. When you see a noise control method in use, try to avoid disturbing it. Also, take extra care to avoid adding to noise levels when noise control methods are in use.
Noise Induced Permanent Threshold Shift (NIPTS)
Noise induced permanent threshold shift is not reversible and cannot be treated medically. At this stage, sounds are difficult to interpret and perceive. Typically, noise induced hearing loss starts in the higher frequencies. It normally first appears at 4,000 and 6,000 Hz. People with this type of hearing loss have difficulty hearing consonant sounds and understanding speech. If damaging noise exposure continues, hearing loss can spread to lower frequencies also. In some cases, hearing aids can help. However, there is no medical procedure that can restore hearing to normal.
What is Noise?
Noise is defined as an unwanted sound. Sound consists of pressure changes in a medium (usually air), caused by vibration or turbulence. Noise is measured by its frequency, which determines how high or low pitched the sound is. High frequency sound can be more damaging to hearing than low frequency sound. Noise is also measured by its intensity, measured in decibels (dB). Sound pressure or noise is measured on a logarithmic scale, which means a small increase in decibels represents a large increase in sound energy. In particular, an increase in intensity by a unit of 10 decibels results in a ten-fold increase in power. For example, a 30 dB sound is 10 times more powerful than a 20 dB sound. A 40 dB sound is 10 times more powerful than a 30 dB sound and is 100 times more powerful than a 20 dB sound.
Monitoring & Testing Requirements As a rule of thumb, if employees must raise their voice to be heard, the area may have a noise hazard.
Noise monitoring is required when exposures are at or above 85dB. If employers suspect a noise hazard they should conduct noise monitoring. If an employee is exposed to 85 or more decibels during an 8 hour work day the employee must be placed in a hearing conservation program.
Permissible Noise Exposures
OSHA provides the range of permissible noise exposures in 29 CFR 1910.95. If levels of noise exceed these permissible levels, OSHA requires employers to provide protection against the noise. Some states require employers to meet more stringent standards. Be sure to check your state's guidelines.
Workplace Noise Monitoring
OSHA requires employers to assess the work environment when employees are exposed to noise at or above 85 dB measured on the A scale (slow response) averaged over 8 working hours. The exposure measurement should include all continuous, intermittent, and impulsive sound levels from 80 to 130 decibels. When workers move around a lot, when there are big changes in sound levels in different areas, or when the noise is impulse noise, the employer may use representative samples to determine the appropriate hearing protection devices.
Temporary and Permanent Hearing Loss
Temporary hearing loss results from short-term exposures to noise. Also referred to as temporary threshold shift, it is a change in the level of sound that a person can just barely hear. Typically, normal hearing returns after a period of rest. Permanent hearing damage can result from prolonged exposure to excessive noise levels over a period of time. Individuals who regularly sustain temporary threshold shifts will eventually sustain permanent hearing loss or noise induced permanent threshold shift (NIPTS).
Employee Participation
The key to an effective hearing conservation program is employee participation. When excessive noise cannot be engineered out or taken care of by administrative measures, an employer must provide proper hearing protection to all employees. However, the employee must cooperate with the hearing conservation program for it to be effective. Understanding the long-term risks of noise exposure is a first step that employees can take in cooperating and participating in the hearing conservation program.
In the OSHA hearing conservation regulations, employer responsibilities are clearly defined. When employees are exposed to more than 85 decibels over an 8-hour period, the employer must provide a hearing conservation program.
The program should include: Noise monitoring Hearing tests Hearing protection Record-keeping An annual training program for hearing protection.
When noise levels exceed the standard, employers are required to administer a continuing, effective hearing conservation program. The employer must follow specific requirements in order to be in compliance with the OSHA standard. The employer must meet certain:
Training requirements Monitoring and testing requirements Record-keeping requirements.
Before you use your hearing protection, make sure it works. Test your plugs before work.
Try talking out loud. Your sound level should be louder when your earplugs are in. If your sound level isn't louder, reinsert the earplugs for a better fit.
Training Requirements
Workers exposed to time-weighted averages (TWAs) of 85 decibels and above must be trained every year in the: Effects of noise on hearing Purpose, advantages, disadvantages, and effectiveness of hearing protectors Selection, fitting, use, and care of hearing protectors Purpose and procedures of audiometric testing. There is no cure for noise-induced hearing loss, so the prevention of excessive noise exposure is the only way to avoid hearing damage.